Effect of temperature on compressibility properties of 0.1, 0.5 and 1.0 molal solutions of alkali metal halides. Part 1. Aqueous solutions of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, rubidium chloride and rubidium iodide in the 278.15 K to 353.15 K temperature range

Accepted Manuscript Effect of temperature on compressibility properties of 0.1, 0.5 and 1.0m solutions of alkali metal halides. Part 1. Aqueous solutions of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, rubidium chloride and rubidium iodide in the 278.15K to 353.15K temperature range

Alexander Apelblat PII: DOI: Reference:

S0167-7322(17)32807-6 doi: 10.1016/j.molliq.2017.07.110 MOLLIQ 7689

To appear in:

Journal of Molecular Liquids

Received date: Revised date: Accepted date:

26 June 2017 20 July 2017 25 July 2017

Please cite this article as: Alexander Apelblat , Effect of temperature on compressibility properties of 0.1, 0.5 and 1.0m solutions of alkali metal halides. Part 1. Aqueous solutions of sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, rubidium chloride and rubidium iodide in the 278.15K to 353.15K temperature range, Journal of Molecular Liquids (2016), doi: 10.1016/ j.molliq.2017.07.110

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ACCEPTED MANUSCRIPT 1

Effect of Temperature on Compressibility Properties of 0.1, 0.5 and 1.0 Molal Solutions of Alkali Metal Halides. Part 1. Aqueous Solutions of Sodium Chloride, Sodium Bromide, Sodium Iodide, Potassium Chloride, Potassium Bromide, Potassium

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Iodide, Rubidium Chloride and Rubidium Iodide in the 278.15 K to

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Alexander Apelblat*

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353.15 K Temperature Range.

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Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel

Abstract

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Sound velocities in aqueous 0.1 mol.kg-1 , 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions of NaCl, NaBr, NaI, KCl, KBr, KI, RbCl and RbI were measured at 1 K intervals from T = (278.15 to 353.15) K. Determined sound velocities and densities served to determine the isentropic isothermal compressibility coefficients, the apparent molar compressibilities, the apparent molar volumes, the isochoric thermal pressure coefficients, cubic expansion coefficients, changes of heat capacities with volume and with pressure, and the hydration numbers. In addition were evaluated the ultrasonic relaxation times and corresponding thermodynamic functions of the activation of the viscous process. Determined parameters are qualitatively correlated with changes in the structure of water when alkali metal halides are dissolved in it. Keywords: Alkali metal halides. Sound velocities. Densities. Isothermal and isentropic

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compressibilities. Apparent molar compressibilities and apparent molar volumes. Isochoric thermal pressure coefficients. Cubic expansion coefficients. Changes of in heat capacities with volume and pressure. Thermodynamic functions of the activation of the

viscous process. Structure of aqueous solutions of alkali metal halides.

*Corresponding author, E-mail: [email protected]

ACCEPTED MANUSCRIPT 2 1. Introduction Compressibility of aqueous solutions of strong electrolytes has been extensively studied in a context of changes in the structure of water over a considerably long period of time. The particular attention has been directed to simplest groups of 1:1 type electrolytes, namely to halides of alkali metals which are major constituents of saline reservoirs, oceans, seas and some lakes [1-32]. Most

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studies were devoted to changes in compressibility as a function of concentration at constant temperature. Only in few investigations sound velocities were measured in 5 K or 10 K temperature intervals. From time to time, they were directed to

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determination of temperatures corresponding to the sound velocity maximum (at

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about 74 C for pure water) and their shifts with concentration of added inorganic salts [33-37].

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Besides studies devoted to thermodynamic properties of solutions, sound velocity determinations are of a huge practical importance in detection of underwater objects by means of sound echoes. Therefore, in electrolyte solutions or in seawater,

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an accurate knowledge of sound velocities as a function of temperature and chemical composition is necessary. Desired accuracy is achieved by frequent calibration of

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applied ultrasonic velocimeters by measuring sound velocities in pure water. Sound velocities in pure water as a function of temperature were determined many times [38-

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44] and they were analyzed by Marczak [45]. In some investigations, in addition to determination of compressibility coefficients, the hydration numbers h(T;m) of electrolytes were evaluated. This was initiated in the 1938-1940 period by Passynski

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[5], but other procedures to calculate h-numbers are known and discussed in the literature [46-60].

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As mentioned above, most of known determinations of sound velocity is performed at one temperature. Only in few cases a limited temperature range is covered, but usually with large gaps between temperatures, and this prevents to perform accurate numerical differentiations of experimental data at constant molality m with regard to temperature T. The literature results are therefore limited only to determination of isentropic and isothermal compressibilities S(T, m) and T(T, m). This disadvantage can be avoided if at fixed molality m sound velocities u(T; m = const.) and densities (T, m = const.) are measured at closely spaced temperature intervals. This permits to express all measured and calculated quantities as

ACCEPTED MANUSCRIPT 3 polynomials of temperature, and accurately perform desired mathematical operations. Carried out in such way measurements were performed at fixed 0.1, 0.5 and 1.0 mol.kg-1 concentrations. They included determinations of densities in aqueous solutions of NaCl, NaBr, NaI, KCl, KBr, KI, RbCl and L-dipotassium tartrate [61-67] and sound velocities in LiCl, Na2CO3 and Na2SO4 solutions [65,66] Determined densities [62] served to obtain the apparent molar volumes V2,(T;m), the cubic

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expansion coefficients (T;m), and the changes of heat capacities CP with pressure (∂CP/∂P)T,m.

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In this investigation, the compressibility properties of aqueous solutions of NaCl, NaBr, NaI, KCl, KBr, KI, RbCl and RbI are examined over a wide temperature

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range, from 278.15 K to 353.15 K. Experimentally measurable quantities, sound velocities u(T; m = const.) and densities (T, m = const.), at 1 K intervals, were

compressibility

S(T;m),

coefficients

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expressed as polynomials of temperature, and they helped to evaluate the isentropic the

apparent

molar

compressibilities

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(T;m)the isochoric thermal pressure coefficients (∂P/∂T)V,m, and changes of the heat capacities CV with volume (∂CV/∂V)T,m. In addition, the ultrasonic (viscous) relaxation times (T;m) and the corresponding thermodynamic functions of activation

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of the viscous process were evaluated. Finally, by applying the Passynski method [5],

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hydration numbers of electrolytes h(T;m) as a function of temperature and concentration were determined.

Measured sound velocities and other derived quantities were compared with

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corresponding results in the literature. Comparison is not simple, because available data is rarely known for exactly 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions.

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And therefore, in such cases, the linearly interpolated and extrapolated values were used. Changes in the structure of water, which are caused by dissolved alkali metal halides are discussed by considering changes in compressibility and volumetric properties of solutions.

2. Experimental Analar grade reagents NaCl, NaBr, NaI, KCl, KBr, KI and RbCl (mass fraction > 0.99) and RbI (mass fraction > 0.98), all from Sigma-Aldrich were used without further purification. Solutions were prepared by mass, by dissolving alkali metal halides in double distilled water.

ACCEPTED MANUSCRIPT 4 Ultrasound measurements were performed in the 278.15 K to 323 K temperature range using a Sing-Around Meter (SAM) constructed in the University of Silesia (Poland). For a more wide temperature range, from 278 K to about 358 K, the velocimeter acquired from Optel Company. (Wroclaw, Poland) was used. In this case, the times of flight of sound were converted to sound velocities by the computer card provided by Optel Company. The sample cells with prepared solutions were

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immersed in a thermostat (± 0.05 K) to reach thermal equilibrium and temperatures were changed in 1 K intervals. The ultrasonic velocimeters were frequently calibrated with water by fixing the value of u1(T) = 1496.73 ms-1 at T = 298.15 K and

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determining deviations at other temperatures from the Marczak equation [45]

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u1(T ) / m  s-1  1.402385 103  5.038813100  5.799136 102 2  (1)

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3.287156 104 3 1.398845106 4  2.78786 109 5   T / K  273.15

This equation is based on critical analysis of available in the literature data for pure water [38-44]. Differences between measured velocities of sound in pure water and

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those derived from the Marczak equation, u1(T), permitted to establish the precision of our measurements. Over entire temperature intervals, the mean value of deviation

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from the above equation was for the University of Silesia apparatus about ± 0.4 ms-1 and for the Optel instrument about ± 0.2 ms-1. In Figure 1 are plotted typical sets of

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u1(T) values for SAM and Optel instruments. As can be seen, deviation from the Marczak equation are more pronounced at higher temperatures, starting from about

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323 K. Reported in this work sound velocities come from the Optel instrument, when SAM apparatus usually served for control purposes. A more detailed discussion about

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accuracy of determined in this investigation quantities will be given below.

3. Results and Discussion 3.1 Thermodynamic quantities derived from measured densities and sound velocities. Using densities (T;m = const.) and sound velocities u(T; m = const.) at fixed concentration m, the isentropic (adiabatic) compressibility coefficient can be evaluated from the Newton-Laplace equation

1 V S (T; m)    

V  P T ,m



1  (T; m)  1    2 (T; m)  P T ,m u(T; m) (T; m)

(2)

ACCEPTED MANUSCRIPT 5 Since the cubic expansion coefficients, (T;m), (isobaric thermal expansibilities) are known from temperature dependence of densities

  ln (T; m)  1 V )P,m     V T T  P,m

 (T; m)  (

and the isobaric heat capacities of solution per unit volume can be taken from literature, the isothermal compressibility coefficient can determined from

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1  V  T 2 (T ; m) T (T ; m)      S (T ; m)  V  P T ,m CP (T ; m)

(4)

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where CP(T;m) = cP(T;m(T;m) and cP(T;m) is the isobaric specific heat capacity.. It is worthwhile to note that the ratio of compressibility coefficients is equal to the

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ratio of heat capacities S(T;m) /T (T;m) = CV(T;m)/CP(T;m), and it follows from Eq. (3) that always T(T;m) > S(T;m). From knowledge of (T;m) and T(T, m) values, it

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is possible to evaluate the isochoric thermal pressure coefficient

P   (T; m)    T V ,m T (T; m)

(5)

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V (T; m)  

Using determined densities of solutions (T;m), and that of pure

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water H2O (T ) , which is based on water densities taken from [68]

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H2O (T )/ g  cm-3  0.9999727  4.035198105  7.090436106 2  3.554779 108 3 1.00270981010 4   T / K  273.15

(6)

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the apparent molar volumes are

V (T; m) VH2O (T ) M2 1000  1 1       m (T, m) m  (T; m) H2O (T ) 

(7)

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V2, (T; m) 

where M2 is the molar mass of dissolved in water alkali metal halide. Differentiation of Eq. (7) with regard to pressure P gives the apparent molar compressibility

 V (T; m)  S (T; m)M2 1000  S (T; m) S,H2O (T )  K2, (T; m)   2,        P  ( T ; m ) m  ( T ; m ) H2O (T )   T ,m  Applying the Maxwell relation to differentials of the internal energy and enthalpy

(8)

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  P   dU  CV dT  T    P dV   T V    V   dH  CPdT  V  T    dP  T P  

(9)

The volumetric and thermal properties of solutions are interrelated

(10)

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 2 P   CV   V   V   T  T 2   T  T   g(T ; m)  T    

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 2V   CP   P   T  T 2    f (T; m)  T  

Functions, f(T;m) and g(T;m), are of importance because they give an indication about

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changes in the structure of water when solutes are dissolved in it [.61-67,69]. From compressibility measurements, it is also possible to evaluate the

1000  T (T; m)  H2O (T )  1   mMH2O  T ,H2O (T )  (T; m) 

(11)

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h(T; m) 

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hydration numbers of electrolytes h(T;m), basing on the Passynski method [5]

If viscosities (T;m) of investigated solutions are known, the ultrasonic

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(viscous) relaxation times  (T; m)  S (T; m) (T; m)  and thermodynamic

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functions of activation of viscous process can be determined

(12)

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  h G (T ; m)  RT ln    kT (T ; m)  G (T ; m)  S (T ; m)   T   G (T ; m)  H (T ; m)  T S (T; m)

where h and k denote the Planck and the Boltzmann constants. Sound velocities and the isentropic compressibility coefficients can be correlated by empirical relations [70-74]

R1(m)  M12u1/3 (T; m)/ (T; m) 7 R2 (m)  1/ S (T ; m) (T ; m) M12 R3 (m)  1/ 7 S (T; m)(T; m) M12  x1M1+x2M2

(13)

ACCEPTED MANUSCRIPT 7 R1(m), R2(m) and R3(m) functions are useful for electrolyte solutions, because they are nearly independent of temperature T and linearly depend on concentration m.

3.2 Data reduction and accuracies of determined thermodynamic quantities. It should be taken into account that reported sound velocities u(T; m) are only experimental quantities, when densities (T;m) were evaluated from polynomials

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given in our previous investigations [61,62,65]. Specific heat capacities, in some cases densities and viscosities were taken from literature [68, 75-112]. They were also

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expressed as polynomials of temperature, to perform interpolations for desired concentrations. A very accurate specific heat capacities (from 278.15 K to 393.15 K

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and at 0.35 MPa) coming from the Woolley group [82,86,89-93,95] and viscosities determined by Isono [104,107] (from 288.15 K to 328.15 K) were preferred in

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calculations.

Volumetric, compressibility and other physical properties are usually known

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as a function of concentration at one, sometime at few temperatures, but not at constant molality m. Therefore, for mathematical convenience (calculation of first and second derivatives with respect to temperature T at fixed m), all quantities were

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smoothed by fitting them to polynomials in the form

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Y ( )/[unit]  A  B  C 2  D 3  E 4  F 5   T / K  273.15

(14)

where the dimensionless adjustable coefficients A, B, C, D, E and F were evaluated by an unweighted least-squares method. It was observed that deviations of sound

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velocities, u(;m) = [u(T;m)exp - u(T;m)calc,] were randomly distributed within the estimated accuracy of our experiments.

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Determined sound velocities depend on the calibration of equipment with pure water u1(T) and therefore u(T:m) can not actually be considered as having absolute values. As can be seen in Figure 1, determined u1(T) values vary in experiments, depend on a quality of used water and other factors. Unfortunately, in investigations available in the literature, u1(T) values are rarely mentioned. Besides, the changes in sound velocity caused by dissolved solute, u(T:m) = [u(T:m) – u1(T)], called by Millero et al. [27,113] as the relative sound velocities are also only occasionally reported. Since u(T:m)/u(T:m) << 1, only changes in sound velocities give an adequate picture when results from different investigations are compared as a function

ACCEPTED MANUSCRIPT 8 of concentration or temperature. On the other hand, the exact absolute values of u(T:m), which are large numbers, are less important when the isentropic (adiabatic) coefficients S(T;m) are calculated from them. The accuracy of S(T;m) depends only on sound velocity and density uncertainties u(T:m) and (T;m), because errors associated with preparation of solutions of concentration m are usually very small and can be neglected. Then, it follows from equation (2) that

 u(T : m) (T : m)  u(T : m) (T : m)

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S (T : m)   S (T : m) 2

(15)

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Accuracies of reported here thermodynamic quantities are illustrated for solutions with lowest concentration of potassium chloride where expected errors have

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maximal values. For 0.1 mol.kg-1 solution of KCl at 298.15 K, we have M2 = 74.55 g.mol-1, u(T:m) = 1501.6 m.s-1, u(T:m) = ± 0.5 m.s-1, (T;m) = 1.00118 g.cm-3 ,

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(T;m) = ± 0.00001 g.cm-3, and S(T;m) = 4.43.10-10 Pa-1. Thus, it follows from equation (15) that the limits of the expected error are ± 2.99.10-13 Pa-1, i.e. about 0.07

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percent only. In most cases, the first term in the brackets which is associated with sound velocities is a predominant term and therefore Fq. (15) can be reduced to

 u(T : m) u(T : m)

(16)

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S (T : m)   2S (T; m)

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Difference between the isothermal and isentropic coefficients is a small quantity T;m[T(T;m) - S(T;m)] = 5.11.10-12 Pa-1, it depends on accuracies of the isobaric thermal expansibility, heat capacity and thermal control in experiments.

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From Eq.(4) it follows that

 (T ; m)  CP (T ; m) (T ; m) T     (T ; m) CP (T ; m) (T ; m) T

(17)

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  (T ; m)   (T ; m) 2

Introducing values of T = ± 0.05 K, T = 298.15 K, CP(T;m) = ± 0.01 J.g-1, CP(T;m) = 4.138 J.g-1, (T;m) = ± 2.10-6 K-1 and (T;m) = 2.67.10-4 K-1 into Eq.(17) we have that (T;m)±9.0.10-14 Pa-1 which gives the error of about 2.0 percent. The first term in Eq.(17) is a predominant term, when in most cases three other terms can be neglected. However, if the isobaric thermal expansibility (T;m) is less accurate, with estimated much larger error, for example (T;m) = ± 1.10-5 K-1, then the uncertainty limits raise to about 9.0 percent. The uncertainty of the isochoric thermal pressure coefficient depends on uncertainties of (T;m) and T(T;m)

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V (T ; m)  V (T ; m)

 (T ; m) T (T ; m)   (T; m) T (T; m)

(18)

The ratio T(T;m)/T(T;m) can be replaced by S(T;m)/S(T;m) in Eq.(18) because they have similar values. Using V(T;m) = 5.95.10-5 Pa.K-1, the expected error is ± 4.86.10-7 Pa.K-1, which is rather small, about 0.8 percent. The second term in the brackets is smaller than the first term, but both are important.

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If properties of pure water are considered to be exact (the isentropic coefficient S,1(T) = 4.477.10-10 Pa-1 and density (T) = 0.99705 g.cm-3 ), the error in

 (T : m)(T : m) 1  1000  M2  S (T : m)  S   (T : m)  m  (T : m)

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 K2, (T : m)  

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the apparent molar isentropic compressibility is

(19)

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For 0.1 mol.kg-1 solution of KCl at 298.15 K, the apparent molar isentropic compressibility is K2, (T;m) = -3.33.10-8 cm3.mol-1.Pa-1 and the error from Eq. (19) is

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K2, = ± 3.06.10-9 cm3.mol-1.Pa-1. As expected for dilute solutions, its value is rather large, about 9.2 percent, but it decreases rapidly with increasing concentration m. The second term in brackets in equation (19) is small as compared with the

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approximated by

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first term, and the error in the apparent molar isentropic compressibility can be

 K2, (T : m)  

2S (T : m)  1000   u(T : m) M2   (T : m)  m  u(T : m)

(20)

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The expected error of the apparent molar volumes V2,(m T), if density of pure water is assumed to have an exact value, is

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V2, (T : m)    M2  

1000   (T : m) m   2 (T : m)

(21)

For considered potassium chloride solution we have V2,(m T) = 33.09 cm3.mol-1 and

V2,(m;T) = ± 0.10 cm3.mol-1, which is about 3.0 percent. Finally, from Eq.(11) the uncertainty associated with hydration numbers is

 h(T ; m)  

1000 H2O (T )  (T ; m)(T; m) T (T ; m)  T m MH2O T , H2O (T )(T ; m) (T; m)

(22)

ACCEPTED MANUSCRIPT 10 and its value is h = ± 0.4. Considering that hydration number is h = 8.1 the estimated the error is about 4.7 percent, but similarly as for other quantities, the error decreases quickly with increasing concentration m. 3.2 Sodium halides As expected from sodium halides, the biggest attention has been directed to sodium chloride solutions [1,3-8,10-12,14,17-20,27-29,70,113], considerably less

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interest to sodium bromide solutions [1,3-5,8,11,18,21,23,113,115] or to sodium iodide solutions [1,3-5,19,113]. Unfortunately, in many investigations, sound velocities were determined at one or few temperatures, and sometimes they were even

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presented in graphical form only. Comparison of changes in sound velocity, u(T:m)

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= [u(T:m) - u1(T)], (a more sensitive test than velocities themselves) in sodium chloride solutions, taken from the literature and our results, shows a quite good

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agreement (Figure S1). However, the agreement is less satisfactory, for sodium iodide solutions (Figure S2). With increasing concentration of sodium iodide, and at temperatures above 20 0C, sound velocities are lower than those in pure water,

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u(T:m) < 0 (Figure 2 and S2). Such behaviour is usually attributed to existence of heavy ions in aqueous solutions, which is represented here by the presence of I- ions.

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In solutions of strong electrolytes, the temperature dependence of sound

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velocity u = f(T; m = const.) has a parabolic form with a maximum situated for more concentrated solutions at lower temperatures. However, the fixing of sound velocity maxima is not specially accurate [36,37]. The parabolic form of sound velocity is

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usually interpreted by applying the two-state model for water. Water is assumed to be a mixture of hydrogen-bonded associates and monomeric molecules of water (low density bulky aggregates containing a number of water molecules and high density

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water - monomers of densely packing). Water monomers behave as an “ordinary liquid” where sound velocity decreases with increase of temperature, an opposite behaviour is observed for hydrogen-bonded associates. Thus, these two types of water act differently with regard to temperature T, du(T;m)/dT > 0 for hydrogen-bonded species (increasing in compressibility) and du(T;m)/dT

<

0 for ordinary water

molecules (increasing in density). An equilibrium between these two types of water exists at any given temperature. Two factors, temperature and added electrolyte (structure breakers), reduce a number of hydrogen-bonded species in solution. Thus, sound velocity rises with temperature, but this rise is slowed down when temperature

ACCEPTED MANUSCRIPT 11 increases and finally the maximum of sound velocity appears. Evidently, after the maximum, du(T;m)/dT

= 0, the role played by ordinary water molecules is

predominant. Determined sound velocities u(T;m) of sodium halides and calculated isentropic compressibility coefficients S(T;m) and changes of heat capacities CV with volume (∂CV/∂V)T,m. are presented in Table 1, 2 and 3. Other evaluated

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thermodynamic quantities and physical parameters of solutions are given in Supplementary Content (Tables S1-S6). For sodium halides, the isentropic compressibility coefficients S(T;m) and the isothermal compressibility coefficients

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T(T;m) can be arranged in the following order (H2O) > (NaI) > (NaBr) >

SC

(NaCl). As can be observed in Figure 3, they have concave upward curvature with the minimum at about 40 0C for the isothermal compressibility coefficients, and about

NU

at 60 0C for the isentropic compressibility coefficients. The minima are usually shifted to lower temperatures as concentration m increases. At constant T, both

MA

compressibility coefficients decrease with increasing concentration of dissolved salt. The apparent molar isentropic compressibility expresses the effect of pressure on the partial volume of electrolytes.(T;m) were calculated using values of S(T;m),

D

(T;m), and those of pure water (T) 

S,1(T) from [44]. Functional

PT E

dependence of the apparent molar isentropic compressibility on temperature and concentration is rather complex, but always it is observed that | -(NaCl) | > | -

(NaBr) | > | -(NaI) |. At constant temperature, the apparent molar volumes can

CE

be arranged as V2,(NaI) > V2,(NaBr) > V2,(NaCl) and their values usually increase with concentration. As a function of temperature they have concave downward

AC

curvatures with weak maxima [62]. The isochoric thermal pressure coefficients of pure water V(T) are considerably smaller than those of sodium halides. They increase with temperature and concentration and can be arranged as V(NaI) > V(NaBr) >

V(NaCl) > V(H2O), but differences between them are small. Interrelations between thermal, volumetric and compressibility properties which are expressed in Eq. (10), permits to obtain information about changes in structure of water when an electrolyte is added. There is general agreement that a highly ordered cooperative hydrogen-bonded structure is responsible for the “abnormal” high heat capacity of pure water. If pressure increases, the structure is partially destroyed, and the expected change in heat capacity (∂CP,1/∂P)T will be

ACCEPTED MANUSCRIPT 12 negative, and from Eq. (10), the product of temperature T and the second derivative of volume f(T; m = 0) will be positive. Effect of temperature on the structure of water is similar, but at higher temperatures (or pressures) the product increases only slightly due to the fact that water starts to behave like a “normal” liquid. The isochoric heat capacity of pure water and electrolyte solutions increases with increasing volume because the second derivative of the pressure with respect to temperature is always

PT

positive, g(T;m) = T .(∂2P/∂T2)V,m > 0. Result of dissolved electrolyte on the water structure is less predictable and therefore in order to find changes produced by it, Hepler [69] proposed to consider circumstances at which the ion-ion interactions are

RI

minimal. He suggested to replace the second derivatives of the total volume V(T;m)





. Following Hepler, the product

 



should be negative

NU



SC

with the second derivatives of the partial molar volume of solute at infinite dilution,

for the structure-breaking solutes and usually this product increases with T and the curve is concave downward. For the structure-making solutes, the product is positive,

MA

increases with T and the curve is concave upward. However, it is difficult to apply the Hepler criteria. because the partial molar volumes of solutes at infinite dilution are 

D

determined at each temperature from an extrapolation to zero concentration, and are insufficiently accurate to be differentiated twice with regard to

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temperature. The present author in [65] suggested to modify them by considering behaviour of functions at finite low concentrations, f(T;m) = [f(T;m) - f(T;m = 0)]. Similarly as in the Hepler criteria, the less ordered structure of water is characterized

CE

by f(T;m) < 0 and the more ordered structure by f(T;m) > 0. The same conclusions can be reached if analogous functions g(T;m) = [g(T;m) - g(T;m = 0)], the products

AC

of temperature and changes in the isochoric heat capacity with volume are introduced [66]. In the same way, negative values of g(T;m) are associated with the structurebreaking solutes and positive values with the structure-making solutes. At constant concentration m, the behaviour of f(T;m), f(T;m = 0), g(T;m) and g(T;m = 0) functions for sodium chloride solutions is similar (Figures S3 and S4). The changes in heat capacities with pressure and volume are larger for water only for temperatures lower than about 40

0

C and they are smaller with increasing

concentration of sodium chloride. The crucial information is acquired if the functions f(T;m) and g(T;m) are analyzed for lowest concentrations of electrolytes. In the

ACCEPTED MANUSCRIPT 13 case of m = 0.1 mol.kg-1 sodium chloride solution, f(T;m) has negative values for T < 40 0C, increases with temperature, and at higher temperatures f(T;m) is positive (Figure 4). This means that sodium chloride is the structure-breaking solute at lower temperatures and the structure-making solute at higher temperatures. With increasing concentration of sodium chloride in water, f(T;m) is more negative, and a stronger destruction of water structure is predicted. The same conclusions can be reached from

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behaviour of g(T;m), which are illustrated in Figure 5. For the same solution of sodium chloride, g(T;m) values are negative for about T < 65 0C and above this

RI

temperature g(T;m) values are positive. Once again indicating an existence of two regions with structure-breaking and structure-making solutes. With increasing

SC

concentration m, g(T;m) is always negative, but its behaviour as function of T is more complex than f(T;m). Thus, from both volumetric and compressibility

NU

measurements it can be concluded that with increase of temperature, sodium chloride gradually changes, from the structure-breaking solute to the structure-making solute.

MA

According to f(T;m) = 0 and g(T;m) = 0 values, the change occurs not at the same temperature. However, in dilute solutions, both functions can not be considered as especially accurate (small differences between two large terms), and this explains

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disagreement between them. If sodium halides are compared, all of them behave

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similarly as is illustrated in Figures 6 and 7. At low temperatures, the destructive character of solute can be arranged as NaI > NaCl > NaBr (at room temperatures as NaI > NaBr > NaCl) and at higher temperatures, the structure-making character is

CE

reversed, NaBr > NaCl > NaI. It follows from compressibility measurements that the change from structure-breaking to structure-making solute occurs at lowest

AC

temperature for sodium chloride and highest temperature for sodium iodide, i.e. the temperature of change increases with the size of halide ion. This is in an agreement with the Marcus classifications of ions at room temperatures [117,118]. He postulated that ions can be arranged according to their structure-breaking effect as I- > Br- > Clwhen Na+ is a borderline ion. Thus, at room temperatures, the cooperative effect of both cation and anion will produce less structured water. Water-ion interactions are often expressed in terms of hydration numbers h(T;m) which are assigned to salts or to individual ions. Available from numerous investigations hydration numbers of sodium halides are determined or estimated from variety of theoretical and experimental methods [24,46-60,68,119-128]. Depending on

ACCEPTED MANUSCRIPT 14 how they are defined or by what techniques they are determined their values differ considerably. Usually, reported hydration numbers at infinite dilution belong to one of two groups. In majority of investigations they are always less than ten and have similar values. However, recently, Onori and coworkers [50,123,124] and Afanasiev and coworkers [53-56,59], postulated considerably larger values of hydration numbers, sometimes more than twenty. Thus, the “compressibility” hydration

PT

numbers should be considered with some reservation because of their questionable models for interaction of ions with water in their immediate vicinity. If they are determined using the Passynski method for estimation of h values [5], they belong to

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the first group, like in this investigation (Supplementary Content, Tables S1, S3 and

SC

S5). In dilute solutions differences between hydration numbers of sodium halides are small. Derived for concentrated solutions hydration numbers can be arranged in the

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following order h(NaI) > h(NaBr) > h(NaCl). Hydration numbers decrease with concentration m, and with temperature T, and they approach the limiting value at high temperatures (Figure 8).

MA

The ultrasonic (viscous) relaxation times (T;m) are similar for sodium halides (viscosity of sodium bromide solutions is known only up to 70 0C). They slightly

D

decrease with concentration, but more strongly with increase of temperature. This means that also the Gibbs free energy of activation G*(T;m) are also similar and

S1, S3 and S5).

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always H*(T;m) > TS*(T;m) >> G*(T;m) > 0 (Supplementary Content, Tables

CE

Functions introduced in Eq. (13), R1(m), R2(m) and R3(m), over the 278 K to 353 K temperature range reproduce the compressibility parameters with less than 1.5 percent error, the best from them are R3(m) functions with the standard deviation of

AC

about ± 5.5 10-6 Pa1/7.m3.mol-1

 x M +x M  R3 (m)/ Pa1/7  m3  mol-1  106  1/ 71 1 2 2  S (T; m)(T; m)  R3 (NaCl,m)  395.51 6.560 m* R3 (NaBr,m)  395.41 8.788 m* R3 (NaI,m)  394.78 13.691m* m*  m /1 mol  kg-1

3.3 Potassium halides

(23)

ACCEPTED MANUSCRIPT 15 Most determinations of sound velocities in solutions of potassium halides were performed with potassium chloride [1,3,5-7,9,11-13,14,16-19,20,23-25,28,33,79,113], less measurements were carried out with potassium bromide [1,5,7,9,1113,19,21,24,25,79,113,115],

and

considerably

less

with

potassium

iodide

[1,3,5,9,13,16,54,113]. Similarly as with other alkali metal halides, measurements were performed mainly in solutions of different concentrations, less at different

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temperatures. Changes in sound velocity, u(T:m) = [u(T:m) - u1(T)], for potassium chloride, potassium bromide and potassium iodide solutions, calculated from

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available in the literature results, are illustrated in Figures S5,. S6 and S7 respectively. As can be seen, in the case of potassium chloride, the agreement is acceptable for

SC

dilute solutions, but less for 1.0 mol.kg-1 solutions (Figure S5). Usually, sound velocities measured in solutions of sodium halides are more accurate than those in

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solutions of potassium halides. Sound velocities in solutions of potassium halides are always higher than those in pure water, u(T:m) > 0 and u(KCl) > u(KBr) > u(KI). However, contrary to sodium iodide solutions, where it was observed that u(T:m) <

MA

0 (Figure 4), in potassium iodide solutions we have always u(T:m) > 0. Determined sound velocities u(T;m) of potassium halides and calculated from them

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thermodynamic quantities (physical properties of solutions were taken from literature)

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are reported in Table 4, 5 and 6 and in Supplementary Content (Tables S7 - S12). At constant temperature, both S(T;m) and T(T;m) of potassium chloride solutions decrease with increasing concentration (Figure 16). The same behaviour is

CE

observed in solutions of potassium bromide and potassium iodide. The apparent molar isentropic compressibilities (T;m)decrease with concentration m, and their

AC

absolute values can be arranged as | -(KI) | > | -(KCl) | > | -(KBr) |, but differences between potassium chloride and potassium bromide are small. And, this order differs from that mentioned above for sodium halides. A typical behaviour of the isochoric thermal pressure coefficients V(T;m) is illustrated in the case of potassium bromide solutions in Figure 10. They increase with temperature and concentration and can be arranged in the following order V(KI) > V(KBr) > V(KCl) > V(H2O). Similarly as with sodium halides, the apparent molar volumes of potassium halides increase with molecular mass V2,(KI) > V2,(KBr) > V2,(KCl) and have concave downward curvatures with weak maxima. Their behaviour as a function of concentration m and temperature T is rather complex. This can be demonstrated by

ACCEPTED MANUSCRIPT 16 plotting V(T;m) values for sodium iodide and potassium chloride solutions. As can be observed in Figure S8, the apparent molar volumes of sodium iodide solutions increase monotonically with concentration m, but those of potassium chloride have an irregular character. Similarly as for sodium halides, we have V2,(KI) > V2,(KBr) > V2,(KCl) and usually their values increase with m and have weak maxima [62]. If behaviour of functions f(T;m) = [f(T;m) - f(T;m = 0)] and g(T;m) =

PT

[g(T;m) - g(T;m = 0)] is examined at lowest concentration (f(T;m) = T .(∂2V/∂T2)P,m and g(T;m) = T .(∂2P/∂T2)V,m.), then changes in the water structure caused by dissolved

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potassium halides can be predicted. As pointed out above, these functions replace the Hepler criteria for establishing the nature of solutes [65]. In Figure 11 are plotted

SC

f(T;m) values and in Figure 12 g(T;m) values for 0.1 mol.kg-1 and 0.5 mol.kg-1 solutions of potassium halides. There is a similarity in behaviour of both functions,

NU

but f(T;m) = 0 appears at lower temperatures than g(T;m) = 0. As mentioned above, the less ordered structure of water is characterized by f(T;m) < 0 and g(T;m) < 0

MA

and the more ordered structure by f(T;m) > 0 and g(T;m) > 0. Differences in the change of molar heat capacities with pressure f(T;m) for 0.1 mol.kg-1 potassium halide solutions (Figure 11) have concave upward curvatures and they predict that

D

below 40 0C dissolved electrolytes act as the structure-breaking solutes and above this

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temperature as the structure-making solutes. With increasing concentration, f(T;m) and g(T;m) are always negative indicating that potassium halides destroy water structure over entire temperature range. It is worthwhile also to note that there is a

CE

gradually change in curvature of f(T;m) function, from concave upward to concave downward. If differences in the change of molar heat capacities with volume g(T;m)

AC

are plotted as a function of temperature (Figure 12), it follows that the change from the structure-breaking solute to the structure-making solute is shifted to higher temperatures in the following order KBr > KCl > KI. Over the entire temperature range, the curvature of g(T;m) changes from concave downward to concave upward for dilute and concentrated solutions of potassium chloride and potassium bromide. The curvature in the case of potassium iodide solutions is always concave upward. Usually, g(T;m) curves have a more complex form than f(T;m) curves (see Figures 11 and 12). Thus, an examination of determined volumetric and compressibility properties leads one again to conclusion about the existence of two temperature regions. At low temperatures, potassium halides behave as the structure-breaking

ACCEPTED MANUSCRIPT 17 solutes and at higher temperatures, as the structure-making solutes. The destructive character of potassium halides is evident considering that the structure-breaking effect of K+ cation is close to that of Cl- anion, and all ions (K+, Cl-, Br- and I-) are structurebreaking ions [117,118]. However, if particular potassium halide is considered,. the strength of ordering effect at high temperatures is not certain. From g(T;m) curves it can be deduced that they can be arranged as KI > KCl > KBr, but when basing on

PT

f(T;m) curves the order is nearly reversed. Hydration numbers h(T;m) of potassium halides, if calculated using the

RI

Passynski method [5], can be arranged in the following manner h(KI) > h(KBr) > h(KCl) (Figure 13). This order and h(T;m) behaviour as a function of m and T is

SC

similar to that observed for sodium halides. Hydration numbers decrease with increase of concentration and temperature, and at higher temperatures they approach the

NU

limiting values. As can be expected, their values are considerably lower than those based on other calculation procedures [50,53-56,59,123,124].

MA

Since viscosities and the isentropic compressibility coefficients of solutions decrease with increase of concentration and temperature, the ultrasonic relaxation

4 3

times,  (T; m)  S (T; m) (T; m)  behave similarly. The ultrasonic relaxation times

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D

of water exceed those of alkali metal halides, (T;0) > (T;m), and the ultrasonic relaxation times of sodium halides are greater than those of corresponding potassium halides: (NaCl) > (KCl), (NaBr) > (KBr) and (NaI) > (KI). Differences between

(T;m) values of different halides are rather small and therefore they are better visibly

CE

if expressed as (T;m) = [(T;0) - (T;m)]. At high temperatures, as can be observed in Figure 14, there is no significant difference in (T;m) and (T;0) values, and

AC

therefore (T;m) → 0.

Thermodynamic functions of activation of the viscous process were calculated using the ultrasonic relaxation times (see Eq. (12)) and they satisfy the following order H*(T;m) > TS*(T;m) >> G*(T;m) > 0. As expected, small differences in

(T;m) values lead to small differences in G*(T;m). The Gibbs free energies of activation. have small positive values and decrease linearly with increase of temperature. The same is observed for the enthalpy H*(T;m) and entropy TS*(T;m) terms at low temperatures, but at high temperatures, they behave differently, they increase with increasing temperature (Figure 15).

ACCEPTED MANUSCRIPT 18 Similarly as for sodium halides, R3(m) functions give the best representation of compressibility parameters for potassium halides

R3 (KCl,m)  375.72 19.680 m* R3 (KBr,m)  395.47 12.423m* R3 (KI,m)  395.43 18.752 m*

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(24)

m*  m /1 mol  kg-1

RI

Over the 278 K to 353 K temperature range, the expected error is about 1.5 percent,

SC

and the standard deviation is of about ± 5.6 10-6 Pa1/7.m3.mol-1

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3.4 Rubidium halides

Sound velocities in solutions of rubidium halides, as well as in cesium halides, are only rarely known in the literature [20,22,23,28,113,114]. Rubidium chloride 0

MA

solutions were considered by Gross et al. [20] at 22.5

0

C, Millero et al. [113] at 25

C. At the same temperature, Gucker and Stubley [23] measured compressibility Tyunina [114] reported

D

coefficients also of cesium chloride. Afanas’ev. and

hydration numbers, based on sound velocities in concentrated solution of rubidium

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chloride (m > 0.8 mol.kg-1) from 15 0C to 45 0C. In graphical form, in a wide temperature interval, from 30 0C to 85 0C, Uedaira and Suzuki [28] presented sound velocities in 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions of rubidium chloride and cesium

CE

chloride. Sound velocities in rubidium bromide solutions are unknown in the literature. There is only one investigation dealing with rubidium iodide solutions

AC

which was performed by Satyavati [22]. She measured sound velocities in a number of rubidium iodide solutions from 35 0C to 55 0C, but unfortunately her results are presented graphically. In the case of rubidium chloride solutions, the agreement between available literature results and reported here is very satisfactory (Figure S9 and Table 7). Sound velocities in rubidium iodide solutions in [22] are given for different that our concentrations, but generally they are consistent with our sound velocities (Table 8). As can be observed in Figure S10, sound velocities in rubidium iodide solutions are always lower than those of pure water u(T:m) < 0 and their values decrease with increase of concentration. On contrary, sound velocities in rubidium chloride solutions are always higher than those in pure water, u(T:m) > 0,

ACCEPTED MANUSCRIPT 19 and their values increase with increase of concentration. Thus, for all concentrations and temperatures sound velocities can be arranged in the following series u(RbCl) > u(H2O) > u(RbI). However, if the isentropic and isothermal compressibility coefficients, the apparent molar compressibilities and the apparent molar volumes are considered, we have the following order: (H2O) > (RbI) >(RbCl); | -(RbCl) | > | -(RbI) | and V(RbI) > V(RbCl) (Supplementary Content Tables S11-S14).

PT

Since heat capacities of rubidium iodide solutions are known only at 25 0C [80], in calculation of isothermal compressibility coefficients at other temperatures, they were

RI

replaced by heat capacities of potassium iodide solutions. However, in order to have the same values at 25 0C, these heat capacities were shifted, by multiplying them by

SC

the factor 0.9951 for 0.1 mol.kg-1 solutions, 0.9771 for 0.5 mol.kg-1 solutions and 0.9610 for 1.0 mol.kg-1 solutions.

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The qualitative effect of dissolved rubidium halides on the water structure can be established by considering behaviour of f(T;m) = [f(T;m) - f(T;m = 0)] and

MA

g(T;m) = [g(T;m) - g(T;m = 0)] functions at lowest concentration. In Figure 16 are plotted f(T;m) values of 0.1 mol.kg-1 and 1.0 mol.kg-1 solutions of rubidium chloride and rubidium iodide. As can be seen, their behaviour is different, the rubidium

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chloride curves have concave downward curvature when those of rubidium iodide

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have concave upward curvature. In 0.1 mol.kg-1 rubidium chloride solutions, f(T;m) is already positive at room temperatures, but it value at higher temperature is close to zero (Figure 16). Thus, rubidium chloride is the structure-breaking solute at low

CE

temperatures and the structure-making solute at higher temperatures, but considering that the accuracy of f(T;m) is not high (small difference between two large

AC

quantities), the temperature of the change is not certain. In more concentrated solutions, rubidium chloride is always the structure-breaking solute. In the case of rubidium iodide solutions, the existence of two temperature regions is more evident. At temperatures lower than 70 0C, rubidium iodide destroys the water structure and above this temperature it behaves as the structure-making solute. With increasing concentration, the temperature of change is shifted to higher temperatures (Figure 16). If g(T;m) functions are analyzed, once again the curvature of curves is similar to those of f(T;m), the rubidium chloride curves have concave downward curvature and the rubidium iodide have concave upward curvature. Over entire temperature range, rubidium chloride is the structure-breaking solute (g(T;m) is negative and is more

ACCEPTED MANUSCRIPT 20 negative with increasing concentration, see Figure 17). On contrary, rubidium iodide has two distinct temperature regions. At temperatures higher than about 50 0C it is the structure-making solute and the temperature of change is shifted to higher temperatures for more concentrated solutions. The predictions based on volumetric and compressibility properties are very similar, but not exactly the same. However, from an examination of f(T;m) and g(T;m) functions it is clear that with increase of

PT

temperature dissolved in water rubidium chloride and rubidium iodide behave differently. Rubidium chloride is nearly always the structure-breaking solute, when

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rubidium iodide at higher temperature helps to preserve the water structure. Hydration numbers h(T;m) of rubidium iodide are significantly higher than

SC

those of rubidium chloride. They decrease with increase of concentration and temperature, and at higher temperatures they approach the limiting values. (Figure

NU

18). As expected, their values are considerably lower than those based on other [50,53-56,59,123,124] than the Passynski procedure [5]. It is worthwhile also to note that at high temperatures rubidium iodide is nearly unhydrated.

MA

Calculated from the ultrasonic relaxation times (see Eq. (12), (BrCl) >

(RbI)) the thermodynamic functions of the viscous process are very similar to those

D

observed for other alkali metal halides H*(T;m) > TS*(T;m) >> G*(T;m) > 0.

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Their functional form is similar for rubidium chloride and rubidium iodide solutions at low temperatures, but their behaviour is different at high temperatures (Figure 19). For rubidium halides, R3(m) functions represent the compressibility parameters by

CE

R3 (RbCl,m)  395.72  9.680m* R3 (RbI,m)  395.52 18.147m*

(25)

AC

m*  m /1 mol  kg-1

and over the 278 K to 353 K temperature range, the expected error is about 1.4 percent, and the standard deviation of is about ± 5.7 10-6 Pa1/7.m3.mol-1

3.5 Alkali metal halides In previous sections, were discussed compressibility properties of aqueous solutions which were composed from the same alkali metal cation, but with different halide anion. Here, aqueous solutions which include the same halide, but different

ACCEPTED MANUSCRIPT 21 alkali metal cations will be briefly discussed by considering only sound velocities, compressibility coefficients and hydration numbers. In case of chlorides, for all concentrations and temperatures, sound velocities decreases in the order u(NaCl) > u(KCl) > u(LiCl) > u(RbCl) > u(H2O) > u(CsCl) (Figure S11). Differences between sound velocities in potassium chloride and lithium chloride solutions [66] are very small. Similar results for alkali metal chlorides were already observed by Uedaira and Suzuki [28]. The combine effect of sound velocity and density of solution (Eq. (2))

PT

gives a quite different series for compressibility coefficients (H2O) > (LiCl) >

RI

(CsCl) > (RbCl) > (KCl) > (NaCl) (Figure 20) Compressibility coefficients of pure water are significantly larger than those of alkali metal chloride solutions, which

SC

means that the compressibility of aqueous electrolyte solutions is smaller than that of pure water. Lower compressibility of electrolyte solutions is caused by introduction of

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incompressible ions to aqueous solutions and by the stabilization of ions by hydration. Lithium chloride solutions are to a some extent different from other solutions, which

MA

have similar compressibility coefficients. The available hydration numbers derived from sound velocity measurements using the Passynski procedure [5] can be arranged as h(RbCl) > h(NaCl) > h(KCl) > h(LiCl). The hydration number decrease with

D

concentration and temperature, and their limiting values in 1.0 mol.kg-1 solutions are

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about seven for rubidium, potassium and sodium chlorides and four for lithium chloride. At room temperatures, only Li+ cation is structure-making ion, Na+ is a borderline ion and all other ions Cl-, K+, Rb+and Cs+ are the structure breaking ions

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with a similar “destructive” effect [117,118]. Basing on electric conductivity measurements, there is nearly no ion pairing in alkali metal halides [126]. These and other facts as sizes of ions and their coordination numbers [127] only in a part are

AC

consistent with the compressibility coefficients order reported above. Only fragmentary data exist for bromides and iodides of alkali metals, and therefore they will be considered together. There are only known sound velocities in 1.0 mol.kg-1 solutions for two bromides, and they are larger than those of pure water u(NaBr) > u(KBr) > u(H2O). In the case of sodium iodide solutions, at temperatures lower than about 30 0C, it is observed that u(NaI) > u(H2O), but above this temperature we have u(H2O) > u(NaI). Other alkali metal iodides have the same sign for the changes in sound velocities over the entire temperature range u(KI) > u(H2O) > u(NaI) > u(LiI) > u(RbI) (Figure S12), and (H2O) > (NaBr) > (RbI) > (NaI) >

ACCEPTED MANUSCRIPT 22

(KBr) > (KI). Values of compressibility coefficients of potassium bromide and sodium and rubidium iodides are very close (Figure 33). Hydration numbers of various alkali metal bromides and iodides behave similarly with change in concentration and temperature, and usually they are higher for iodides than for bromides. Hydration numbers in 1.0 mol.kg-1 solutions can be arranged in the following order h(KI) > h(RbI) > h(NaI) > h(KBr) > h(NaBr), when differences in potassium bromide and sodium bromide solutions are small (Figure 34). Their

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limiting values at high temperatures are h(KI) ≈ 11, h(RbI) ≈ 10, h(NaI) ≈ 9 and h(KBr) ≈ h(NaBr) ≈ 8. As pointed above, at room temperatures, all alkali metal

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cations are structure-breaking ions, similarly as halide anions with I- > Br- > Cl-

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[117,118]. This order is in an agreement when hydration numbers are compared h(MeI) > h(MeBr) > h(MeCl), but this is less evident in the case of compressibility

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coefficients.

4. Conclusions

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Sound velocities in 0.1, 0.5 and 1.0 mol.kg-1 solutions of alkali metal halides were determined the temperature range from 278.15 K to 363.15 K, at 1 K intervals.

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Compressibility and volumetric properties were determined by using sound velocities,

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densities, heat capacities and viscosities of these solutions. All properties of solutions were expressed in the form of polynomials of temperature. Using these polynomials, the isentropic compressibilities S(T;m), the isothermal compressibilities T(T;m), the

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apparent molar compressibilities (T;m)the isochoric thermal pressure coefficients (∂P/∂T)V,m, the apparent molar volumes V2,(T;m), the cubic expansion coefficients (T;m), the changes of heat capacities CV with volume (∂CV/∂V)T,m .and the changes

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of heat capacities CP with pressure (∂CP/∂P)T,m , the ultrasonic (viscous) relaxation times (T;m), the Gibbs free energy G*(T;m), entropy TS*(T;m) and enthalpy H*(T;m) of activation of the viscous process were evaluated. Aplying the Passynski method [5], the hydration numbers h(T;m) of alkali metal halides in investigated solutions were determined. Measured sound velocities and other evaluated quantities were compared with available in the literature results. Reported here compressibility and volumetric properties were qualitatively correlated with changes in water structure. Comparison between different salts gives not always monotonic change in properties with regard to cations and anions. However, it was always observed that at

ACCEPTED MANUSCRIPT 23 low and at room temperatures, alkali metal halides in aqueous solutions behave as the structure-breaking solutes, but with increasing temperature, they gradually become the structure-making solutes. Acknowledgments The author is indebted to Professor Marija Bešter-Rogač, Ljubljana University, Slovenia for converting experimental data from the literature from graphical to digital

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form. I am also grateful to Professor Emanuel Manzurola from Ben Gurion University of the Negev, Beer Sheva, who during a long period of time was involved in mutual research and construction of equipment used in this investigation, and to Zoya

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Orekhova and Paulina Veinner for their excellent technical assistance.

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lithium bromide, sodium bromide and potassium bromide solutions. J. Mol.

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[116] S. Sivaramakrishnalyer, M. Abdulkhadarb. An empirical relation to predict

1191-1194

PT E

ultrasonic velocity in electrolytic solutions. J. Acoust. Soc. Amer. 101 (1997)

[117] Y. Marcus. Viscosity B-coefficients, structural entropies and heat capacities, and the effects of ion on the structure of water. J. Solution Chem. 23 (1994)

CE

831-848

[118] Y. Marcus. Effect of ions on the structure of water: Structure making and

AC

breaking. Chem. Rev. 109 (2009) 1346-1370 [119] T. Sasaki, T. Yasunaga. Studies on hydration by ultrasonic interferometer. V. The change oh hydration of inorganic electrolytes with temperature. Bull. Chem. Soc. Japan 28 (1955) 269-271 [120] A.J. Rutgers, Y. Hendrikx. Ion hydration. Trans. Faraday Soc. 58 (1962) 2184-2891 [121] T. Isemura, S. Goto. Studies of the hydration and the structure of water and their roles in protein structure. II. The hydration of electrolytes by ultrasonic interferometry and its temperature dependence. Bull. Chem. Soc. Japan 37 (1964) 1690-1693

ACCEPTED MANUSCRIPT 34 [122] M. Sakurai, T. Komatsu, T. Nakagawa. The concentration dependence of the apparent molal adiabatic compressibility of electrolytes in water. Bull. Chem. Soc. Japan 54 (1981) 643-647 [123] G. Onori. Ionic hydration in sodium chloride solutions. J. Chem. Phys. 89 (1988) 510-516 [124] G. Onori, A. Santucci. Volumetric properties of 1-1 aqueous electrolyte

[125] A.A.

Zavitsas.

Properties

of

water

PT

solutions and ionic hydration. J. Chem. Phys. 93 (1990) 2939-2945 solutions

of

electrolytes

and

nonelectrolytes. J. Phys. Chem. 105 (2001) 7805-7817

RI

[126] J. Gujt, M. Bešter-Rogač, B. Hribar-Lee. An investigation of ion-pairing of

SC

alkali metal halides in aqueous solutions using the electrical conductivity and the Monte Carlo computer simulation methods. J. Mol. Liquids 190 (2014) 34-

NU

41

[127] S. Vaema, S.B. Rempe. Coordination numbers of alkali metal ions in aqueous solutions. Biophys. Chem. 124 (2006) 192-199

MA

[128] A.K. Soper, K. Weckström. Ion solvation and water structure in potassium

AC

CE

PT E

D

halide aqueous solutions. Biophys. Chem. 124 (2006) 180-191

ACCEPTED MANUSCRIPT 35 TABLE 1 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in sodium chloride solutions. uexp

0.1 mol.kg-1 NaCl

4.57 4.54 4.52 4.49 4.47 4.45 4.43 4.41 4.39 4.37 4.35 4.34 4.32 4.30 4.29 4.27 4.26 4.25 4.24 4.22 4.21 4.20 4.19 4.18 4.17 4.16 4.15 4.14 4.13 4.12 4.12 4.11 4.10 4.09 4.09 4.08 4.08 4.07 4.07 4.06 4.06 4.05 4.05 4.04

MA

1464.8 1467.3 1471.2 1475.4 1479.6 1484.2 1488.0 1491.5 1495.2 1498.4 1501.3 1504.9 1507.7 1510.2 1512.1 1515.4 1517.6 1520.0 1522.4 1524.7 1527.5 1530.2 1532.0 1534.4 1537.1 1538.6 1540.7 1542.8 1544.6 1546.4 1548.5 1550.1 1552.2 1553.5 1554.6 1555.6 1557.2 1559.1 1560.3 1561.6 1562.8 1564.1 1565.7 1566.6

D

0.84 1.13 1.41 1.69 1.96 2.24 2.51 2.77 3.04 3.30 3.56 3.82 4.07 4.32 4.56 4.81 5.05 5.28 5.51 5.74 5.97 6.19 6.41 6.62 6.83 7.04 7.24 7.44 7.64 7.83 8.02 8.21 8.39 8.57 8.75 8.93 9.10 9.27 9.43 9.59 9.75 9.91 10.1 10.2

(∂CV/∂V)T

0.5 mol.kg-1 NaCl

PT E

4.84 4.81 4.78 4.76 4.73 4.70 4.68 4.66 4.63 4.61 4.59 4.57 4.55 4.53 4.51 4.50 4.48 4.46 4.45 4.43 4.42 4.40 4.39 4.38 4.37 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.28 4.28 4.27 4.26 4.25 4.25 4.24 4.23 4.23 4.22 4.22 4.21

CE

1434.3 1438.7 1443.1 1446.7 1451.1 1455.0 1459.0 1462.6 1466.5 1470.1 1473.6 1477.3 1480.2 1483.5 1486.6 1489.3 1492.8 1495.6 1498.1 1501.0 1503.5 1506.0 1508.5 1511.0 1513.5 1515.8 1518.0 1520.2 1522.3 1524.4 1526.3 1528.3 1530.0 1531.7 1533.4 1534.9 1536.7 1538.2 1539.7 1541.2 1542.6 1543.8 1544.9 1546.1

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 NaCl

70.0 69.7 69.4 69.0 68.7 68.3 67.9 67.4 67.0 66.5 66.0 65.5 65.0 64.4 63.9 63.3 62.7 62.1 61.5 60.9 60.2 59.6 58.9 58.2 57.5 56.8 56.1 55.4 54.7 54.0 53.2 52.5 51.7 51.0 50.2 49.5 48.7 48.0 47.2 46.4 45.7 44.9 44.1 43.4

1499.5 1503.0 1505.8 1508.7 1511.9 1515.7 1518.9 1521.8 1525.0 1529.2 1530.2 1536.4 1537.9 1541.3 1544.1 1547.0 1549.0 1551.6 1554.2 1556.2 1558.3 1560.6 1562.7 1564.4 1566.5 1568.0 1569.1 1571.5 1573.3 1574.6 1576.1 1577.4 1578.1 1580.0 1582.2 1583.5 1584.8 1585.8 1586.7 1587.7 1589.0 1590.0 1591.3 1592.6

4.28 4.26 4.24 4.22 4.20 4.18 4.16 4.15 4.13 4.11 4.10 4.08 4.07 4.06 4.04 4.03 4.02 4.01 4.00 3.99 3.98 3.97 3.96 3.95 3.94 3.93 3.92 3.92 3.91 3.90 3.90 3.89 3.88 3.88 3.87 3.87 3.87 3.86 3.86 3.85 3.85 3.85 3.84 3.84

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



62.8 62.5 62.1 61.7 61.2 60.8 60.3 59.8 59.3 58.8 58.2 57.7 57.2 56.6 56.0 55.5 54.9 54.3 53.7 53.2 52.6 52.0 51.4 50.9 50.3 49.7 49.2 48.6 48.1 47.6 47.0 46.5 46.0 45.5 45.0 44.6 44.1 43.7 43.2 42.8 42.4 42.0 41.7 41.3

ACCEPTED MANUSCRIPT 36

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.84 3.84 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.83 3.84 3.84 3.84 3.84 3.84 3.85 3.85 3.85 3.86 3.86 3.87

PT

1593.5 1594.5 1595.2 1595.8 1596.5 1597.1 1597.8 1598.8 1599.1 1599.7 1600.2 1600.5 1600.7 1601.1 1601.4 1601.4 1601.7 1601.7 1602.0 1602.3 1602.3 1602.3 1602.3 1602.3 1602.3 1602.7 1602.3 1602.3 1602.0 1601.7 1601.4 1601.1

RI

49 1547.2 4.21 10.4 1567.5 4.04 42.6 50 1548.4 4.20 10.5 1568.5 4.04 41.9 51 1549.3 4.20 10.7 1569.1 4.03 41.1 52 1550.2 4.20 10.8 1570.1 4.03 40.4 53 1551.1 4.19 10.9 1571.0 4.03 39.6 54 1552.4 4.19 11.1 1571.6 4.03 38.9 55 1553.0 4.19 11.2 1572.3 4.02 38.1 56 1553.6 4.19 11.4 1572.9 4.02 37.4 57 1554.5 4.19 11.5 1573.8 4.02 36.7 58 1555.5 4.18 11.6 1574.4 4.02 36.0 59 1556.1 4.18 11.7 1575.0 4.02 35.3 60 1556.7 4.18 11.9 1575.7 4.02 34.6 61 1557.3 4.18 12.0 1576.3 4.02 33.9 62 1557.6 4.18 12.1 1576.6 4.02 33.2 63 1558.0 4.18 12.2 1577.2 4.02 32.5 64 1558.3 4.18 12.4 1577.5 4.02 31.9 65 1558.6 4.18 12.5 1577.8 4.02 31.2 66 1558.9 4.18 12.6 1578.1 4.02 30.6 67 1559.2 4.18 12.7 1578.5 4.02 29.9 68 1559.5 4.18 12.8 1578.8 4.02 29.3 69 1559.8 4.18 12.9 1578.8 4.02 28.7 70 1560.2 4.19 13.0 1579.1 4.02 28.1 71 1560.2 4.19 13.2 1579.1 4.03 27.5 72 1560.2 4.19 13.3 1579.1 4.03 26.9 73 1560.2 4.19 13.4 1579.1 4.03 26.4 74 1560.2 4.19 13.5 1579.1 4.03 25.8 75 1560.2 4.20 13.6 1579.4 4.03 25.3 76 1560.5 4.20 13.7 1579.1 4.04 24.8 77 1560.2 4.20 13.8 1579.1 4.04 24.3 78 1560.2 4.21 13.9 1579.1 4.04 23.8 79 1559.8 4.21 14.0 1578.8 4.04 23.4 80 1559.5 4.21 14.1 1578.5 4.05 22.9 5 Notation and units: 1 bar = 10 PaK - 273.15

40.9 40.6 40.3 40.0 39.7 39.5 39.2 39.0 38.7 38.5 38.3 38.1 38.0 37.8 37.7 37.5 37.4 37.3 37.2 37.1 37.0 36.9 36.8 36.7 36.7 36.6 36.5 36.4 36.4 36.3 36.2 36.1

ACCEPTED MANUSCRIPT 37 TABLE 2 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in sodium bromide solutions. uexp

0.1 mol.kg-1 NaBr

4.60 4.57 4.56 4.53 4.51 4.49 4.47 4.45 4.43 4.40 4.39 4.37 4.35 4.33 4.31 4.30 4.29 4.28 4.26 4.25 4.24 4.23 4.21 4.20 4.19 4.18 4.17 4.16 4.15 4.14 4.14 4.13 4.12 4.12 4.11 4.10 4.10 4.09 4.08 4.08 4.07 4.07 4.06 4.06

MA

1445.1 1450.6 1452.0 1456.6 1459.8 1463.6 1466.9 1471.2 1474.8 1478.7 1481.2 1485.2 1488.3 1491.4 1494.8 1497.2 1499.8 1502.2 1505.4 1507.7 1509.7 1511.7 1514.3 1516.6 1518.8 1521.3 1523.6 1525.1 1527.0 1528.7 1530.8 1532.3 1533.8 1535.3 1537.1 1538.6 1539.8 1541.7 1543.2 1544.4 1545.3 1546.6 1547.8 1548.7

D

84.6 83.9 83.1 82.3 81.4 80.5 79.7 78.8 77.8 76.9 75.9 75.0 74.0 73.0 72.0 71.0 70.0 69.1 68.1 67.1 66.1 65.1 64.2 63.2 62.3 61.4 60.5 59.6 58.7 57.9 57.0 56.2 55.4 54.7 54.0 53.2 52.6 51.9 51.3 50.7 50.1 49.6 49.1 48.7

(∂CV/∂V)T

0.5 mol.kg-1 NaBr

PT E

4.84 4.81 4.78 4.76 4.74 4.71 4.69 4.67 4.64 4.62 4.59 4.58 4.56 4.54 4.52 4.51 4.49 4.48 4.46 4.45 4.44 4.42 4.41 4.40 4.39 4.38 4.36 4.35 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.28 4.28 4.27 4.26 4.26 4.25 4.25 4.24 4.24

CE

1432.3 1436.0 1440.0 1443.4 1447.7 1451.4 1454.6 1458.1 1462.8 1466.8 1470.4 1473.1 1476.0 1478.9 1482.1 1485.3 1487.6 1490.5 1493.1 1495.5 1497.9 1500.6 1502.7 1505.4 1507.3 1509.2 1511.7 1513.3 1515.3 1517.2 1519.2 1521.1 1522.9 1524.7 1526.2 1528.0 1529.5 1531.0 1532.5 1533.7 1534.9 1536.7 1537.7 1538.9

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 NaBr

73.6 73.1 72.5 71.9 71.3 70.7 70.1 69.4 68.7 68.0 67.3 66.5 65.8 65.0 64.2 63.5 62.7 61.9 61.1 60.3 59.5 58.7 57.9 57.1 56.3 55.5 54.8 54.0 53.3 52.5 51.8 51.1 50.4 49.7 49.0 48.4 47.7 47.1 46.5 45.9 45.4 44.9 44.3 43.9

1467.2 1470.4 1475.4 1478.7 1482.3 1485.4 1488.5 1491.0 1493.3 1496.5 1498.7 1501.2 1503.8 1506.4 1509.0 1511.3 1513.6 1516.2 1518.3 1520.6 1522.4 1524.7 1526.5 1528.2 1530.0 1531.1 1533.1 1534.8 1536.5 1538.2 1539.7 1541.1 1542.5 1544.0 1545.2 1546.4 1548.0 1548.9 1549.8 1551.4 1552.3 1553.2 1554.2 1555.1

4.31 4.29 4.26 4.24 4.22 4.21 4.19 4.18 4.17 4.15 4.14 4.13 4.11 4.10 4.09 4.08 4.06 4.05 4.04 4.03 4.02 4.01 4.00 4.00 3.99 3.98 3.98 3.97 3.96 3.95 3.95 3.94 3.94 3.93 3.93 3.92 3.92 3.91 3.91 3.90 3.90 3.90 3.89 3.89

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



64.9 64.2 63.5 62.8 62.1 61.4 60.7 60.0 59.3 58.5 57.8 57.1 56.4 55.7 55.0 54.3 53.6 53.0 52.3 51.6 51.0 50.3 49.6 49.0 48.4 47.8 47.1 46.5 46.0 45.4 44.8 44.3 43.7 43.2 42.7 42.2 41.7 41.2 40.7 40.3 39.9 39.4 39.0 38.7

ACCEPTED MANUSCRIPT 38

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.89 3.88 3.88 3.88 3.88 3.88 3.88 3.88 3.87 3.87 3.87 3.87 3.87 3.87 3.87 3.87 3.88 3.88 3.88 3.88 3.88 3.88 3.89 3.89 3.89 3.89 3.90 3.90 3.90 3.91 3.91 3.92

PT

1556.0 1557.3 1558.2 1558.8 1559.5 1560.1 1560.7 1561.4 1562.0 1562.6 1562.9 1563.6 1563.9 1564.2 1564.5 1564.8 1565.1 1565.1 1565.4 1565.4 1565.8 1565.8 1565.8 1566.1 1565.8 1565.4 1565.3 1565.0 1565.0 1564.6 1564.3 1564.0

RI

49 1539.8 4.23 48.2 1549.6 4.06 43.4 50 1541.0 4.23 47.8 1550.6 4.06 42.9 51 1541.9 4.23 47.4 1551.5 4.05 42.5 52 1543.2 4.22 47.1 1552.4 4.05 42.1 53 1544.1 4.22 46.8 1553.3 4.05 41.7 54 1545.0 4.22 46.5 1554.3 4.04 41.4 55 1545.9 4.21 46.3 1554.9 4.04 41.0 56 1546.9 4.21 46.1 1555.8 4.04 40.7 57 1547.5 4.21 45.9 1556.8 4.04 40.4 58 1548.1 4.21 45.8 1557.4 4.04 40.2 59 1548.7 4.21 45.7 1557.7 4.04 39.9 60 1549.0 4.21 45.6 1558.3 4.04 39.7 61 1549.6 4.21 45.6 1558.6 4.04 39.5 62 1550.2 4.20 45.6 1559.3 4.03 39.3 63 1550.5 4.21 45.6 1559.6 4.04 39.2 64 1551.2 4.20 45.7 1559.9 4.04 39.0 65 1551.5 4.20 45.7 1560.2 4.04 38.9 66 1551.8 4.21 45.9 1560.2 4.04 38.8 67 1552.1 4.21 46.0 1560.5 4.04 38.7 68 1552.4 4.21 46.2 1560.8 4.04 38.6 69 1552.7 4.21 46.3 1560.8 4.04 38.6 70 1553.0 4.21 46.5 1561.1 4.04 38.5 71 1553.0 4.21 46.8 1561.1 4.05 38.5 72 1553.0 4.21 47.0 1561.1 4.05 38.5 73 1553.3 4.21 47.3 1561.1 4.05 38.5 74 1553.3 4.22 47.6 1561.1 4.05 38.5 75 1553.3 4.22 47.9 1561.4 4.05 38.5 76 1553.3 4.22 48.2 1561.1 4.06 38.5 77 1553.0 4.23 48.5 1561.1 4.06 38.5 78 1553.0 4.23 48.8 1560.8 4.06 38.5 79 1552.3 4.24 49.2 1559.2 4.08 38.5 80 1552.0 4.24 49.5 1559.0 4.08 38.5 5 Notation and units: 1 bar = 10 PaK - 273.15

38.3 37.9 37.6 37.3 37.0 36.7 36.4 36.1 35.9 35.7 35.5 35.3 35.1 34.9 34.8 34.7 34.6 34.5 34.4 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.4 34.5 34.5 34.6 34.8

ACCEPTED MANUSCRIPT 39 TABLE 3 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in sodium iodide solutions. uexp

0.1 mol.kg-1 NaI

4.61 4.59 4.57 4.54 4.52 4.50 4.48 4.46 4.44 4.42 4.40 4.39 4.37 4.35 4.34 4.32 4.31 4.30 4.28 4.27 4.26 4.25 4.23 4.22 4.21 4.20 4.19 4.19 4.18 4.17 4.16 4.15 4.15 4.14 4.13 4.13 4.12 4.11 4.11 4.10 4.10 4.10 4.09 4.09

MA

1432.1 1435.6 1439.2 1443.2 1446.5 1450.2 1453.3 1456.9 1460.4 1463.4 1466.6 1469.7 1472.8 1475.7 1478.5 1481.1 1483.8 1486.1 1488.6 1491.2 1493.4 1495.7 1498.0 1500.4 1502.3 1504.4 1506.3 1508.2 1510.1 1511.7 1513.7 1515.4 1517.1 1518.4 1519.9 1521.3 1522.9 1524.4 1525.4 1526.7 1527.9 1529.1 1530.1 1531.1

D

78.9 78.4 77.8 77.3 76.7 76.0 75.4 74.7 74.0 73.3 72.5 71.8 71.0 70.2 69.4 68.6 67.7 66.9 66.1 65.2 64.3 63.5 62.6 61.8 60.9 60.0 59.2 58.3 57.4 56.6 55.7 54.9 54.1 53.3 52.5 51.7 50.9 50.1 49.3 48.6 47.9 47.2 46.5 45.8

(∂CV/∂V)T

0.5 mol.kg-1 NaI

PT E

4.78 4.75 4.73 4.71 4.69 4.67 4.65 4.64 4.62 4.60 4.59 4.57 4.55 4.54 4.53 4.51 4.50 4.49 4.47 4.46 4.45 4.44 4.43 4.42 4.41 4.40 4.39 4.39 4.38 4.37 4.36 4.36 4.35 4.34 4.34 4.33 4.33 4.32 4.32 4.32 4.31 4.31 4.31 4.30

CE

1439.1 1441.6 1444.8 1448.0 1451.4 1454.5 1457.8 1460.8 1463.8 1466.3 1468.9 1471.5 1474.1 1476.6 1479.3 1481.7 1483.9 1486.4 1488.3 1490.3 1492.6 1494.6 1496.6 1498.3 1500.0 1501.9 1503.5 1505.3 1506.8 1508.2 1509.6 1511.1 1512.6 1513.7 1515.1 1516.4 1517.6 1518.9 1520.0 1521.0 1521.9 1522.9 1523.7 1524.7

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 NaI

66.2 66.1 66.0 65.9 65.7 65.5 65.3 65.0 64.7 64.4 64.1 63.7 63.3 62.8 62.4 61.9 61.4 60.9 60.4 59.8 59.2 58.7 58.0 57.4 56.8 56.1 55.5 54.8 54.1 53.4 52.7 52.0 51.3 50.6 49.8 49.1 48.4 47.6 46.9 46.1 45.3 44.6 43.8 43.1

1439.1 1441.6 1444.8 1448.0 1451.4 1454.5 1457.8 1460.8 1463.8 1466.3 1468.9 1471.5 1474.1 1476.6 1479.3 1481.7 1483.9 1486.4 1488.3 1490.3 1492.6 1494.6 1496.6 1498.3 1500.0 1501.9 1503.5 1505.3 1506.8 1508.2 1509.6 1511.1 1512.6 1513.7 1515.1 1516.4 1517.6 1518.9 1520.0 1521.0 1521.9 1522.9 1523.7 1524.7

4.35 4.33 4.31 4.29 4.27 4.26 4.24 4.22 4.21 4.19 4.18 4.16 4.15 4.14 4.13 4.11 4.10 4.09 4.08 4.07 4.06 4.05 4.04 4.03 4.03 4.02 4.01 4.00 4.00 3.99 3.98 3.98 3.97 3.97 3.96 3.96 3.95 3.95 3.95 3.94 3.94 3.94 3.93 3.93

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



57.5 57.2 56.9 56.6 56.3 56.0 55.6 55.3 54.9 54.5 54.1 53.7 53.2 52.8 52.3 51.8 51.4 50.9 50.4 49.9 49.4 48.9 48.3 47.8 47.3 46.8 46.2 45.7 45.2 44.6 44.1 43.6 43.0 42.5 42.0 41.4 40.9 40.4 39.9 39.4 38.8 38.3 37.8 37.3

ACCEPTED MANUSCRIPT 40

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.93 3.93 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.92 3.93 3.93 3.93 3.93 3.93 3.93 3.94 3.94 3.94 3.95 3.95 3.95 3.96 3.96 3.96

PT

1525.6 1526.2 1526.8 1527.4 1528.0 1528.6 1529.2 1529.5 1529.8 1530.1 1530.7 1531.3 1531.3 1531.6 1531.9 1532.2 1532.5 1532.5 1532.8 1532.8 1532.8 1532.8 1533.1 1532.8 1532.8 1532.8 1532.5 1532.2 1531.9 1531.6 1531.3

RI

49 1525.6 4.30 45.1 1532.2 4.09 42.3 50 1526.2 4.30 44.5 1533.1 4.08 41.5 51 1526.8 4.30 43.9 1534.0 4.08 40.8 52 1527.4 4.29 43.3 1534.9 4.08 40.0 53 1528.0 4.29 42.7 1535.5 4.07 39.2 54 1528.6 4.29 42.1 1536.4 4.07 38.5 55 1529.2 4.29 41.6 1537.1 4.07 37.7 56 1529.5 4.29 41.0 1537.7 4.07 37.0 57 1529.8 4.29 40.5 1538.3 4.07 36.2 58 1530.1 4.29 40.1 1538.9 4.07 35.5 59 1530.7 4.29 39.6 1539.4 4.07 34.7 60 1531.3 4.29 39.2 1540.0 4.07 34.0 61 1531.3 4.29 38.7 1540.3 4.07 33.2 62 1531.6 4.29 38.3 1540.6 4.07 32.5 63 1531.9 4.29 37.9 1541.3 4.07 31.7 64 1532.2 4.29 37.6 1541.6 4.07 31.0 65 1532.5 4.29 37.2 1541.9 4.07 30.3 66 1532.5 4.30 36.9 1541.9 4.07 29.5 67 1532.8 4.30 36.6 1542.2 4.07 28.8 68 1532.8 4.30 36.3 1542.2 4.07 28.1 69 1532.8 4.30 36.1 1542.5 4.07 27.4 70 1532.8 4.30 35.8 1542.8 4.08 26.7 71 1533.1 4.31 35.6 1542.8 4.08 26.0 72 1532.8 4.31 35.4 1543.1 4.08 25.2 73 1532.8 4.31 35.2 1542.8 4.08 24.5 74 1532.8 4.32 35.0 1542.8 4.08 23.8 75 1532.5 4.32 34.9 1542.5 4.09 23.1 76 1532.2 4.32 34.7 1542.2 4.09 22.4 77 1531.9 4.33 34.6 1542.2 4.09 21.7 78 1531.6 4.33 34.4 1541.9 4.10 21.0 79 1531.3 4.34 34.3 1541.6 4.10 20.3 80 1451.3 4.11 19.6 5 Notation and units: 1 bar = 10 PaK - 273.15

36.9 36.4 35.9 35.4 35.0 34.5 34.1 33.6 33.2 32.8 32.3 31.9 31.5 31.1 30.8 30.4 30.0 29.6 29.3 28.9 28.6 28.3 27.9 27.6 27.3 27.0 26.7 26.4 26.1 25.8 25.6

ACCEPTED MANUSCRIPT 41 TABLE 4 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in potassium chloride solutions. uexp

0.1 mol.kg-1 KCl

4.59 4.57 4.54 4.52 4.50 4.47 4.45 4.43 4.41 4.39 4.37 4.36 4.34 4.32 4.31 4.29 4.28 4.26 4.25 4.23 4.22 4.21 4.20 4.19 4.17 4.16 4.15 4.14 4.14 4.13 4.12 4.11 4.10 4.09 4.09 4.08 4.08 4.07 4.06 4.06 4.05 4.05 4.04 4.04

MA

1458.0 1462.6 1466.5 1470.6 1474.1 1477.8 1481.4 1485.1 1488.2 1492.0 1495.2 1498.6 1501.4 1504.7 1507.7 1510.7 1513.5 1516.1 1518.5 1521.3 1523.8 1526.3 1528.6 1531.0 1533.1 1535.2 1537.5 1539.5 1541.3 1543.3 1545.2 1547.1 1548.7 1550.6 1552.1 1553.5 1555.1 1556.5 1558.2 1559.7 1561.1 1562.1 1563.3 1564.6

D

79.1 78.7 78.3 77.9 77.4 76.9 76.4 75.8 75.2 74.6 73.9 73.2 72.6 71.8 71.1 70.4 69.6 68.8 68.0 67.2 66.4 65.6 64.8 63.9 63.1 62.3 61.4 60.6 59.8 58.9 58.1 57.3 56.5 55.6 54.8 54.1 53.3 52.5 51.7 51.0 50.3 49.6 48.9 48.2

(∂CV/∂V)T

0.5 mol.kg-1 KCl

PT E

4.85 4.82 4.79 4.77 4.74 4.72 4.69 4.67 4.65 4.62 4.60 4.58 4.56 4.54 4.53 4.51 4.49 4.47 4.46 4.44 4.43 4.42 4.40 4.39 4.38 4.36 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.29 4.28 4.27 4.26 4.26 4.25 4.24 4.24 4.23 4.23 4.22

CE

1432.6 1437.1 1441.3 1445.4 1449.5 1453.1 1456.7 1461.0 1464.6 1468.2 1471.7 1475.0 1478.4 1481.5 1484.7 1487.2 1490.2 1493.3 1496.3 1499.0 1501.6 1504.5 1506.9 1509.1 1511.6 1513.8 1515.9 1518.2 1520.2 1522.4 1524.2 1526.2 1528.1 1529.8 1531.7 1533.3 1534.8 1536.6 1538.0 1539.3 1540.8 1542.2 1543.3 1544.4

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 KCl

69.6 69.4 69.1 68.9 68.6 68.2 67.9 67.5 67.1 66.6 66.2 65.7 65.2 64.7 64.2 63.6 63.1 62.5 61.9 61.3 60.7 60.1 59.4 58.8 58.1 57.4 56.8 56.1 55.4 54.7 54.0 53.3 52.7 52.0 51.3 50.6 49.9 49.2 48.5 47.8 47.1 46.5 45.8 45.1

1486.7 1490.3 1493.9 1497.6 1501.1 1504.6 1507.4 1510.6 1514.0 1517.2 1519.9 1523.1 1525.9 1528.4 1531.3 1534.1 1536.1 1538.8 1541.2 1543.7 1545.6 1547.7 1549.8 1551.6 1553.6 1555.7 1557.6 1559.4 1561.5 1563.4 1565.1 1566.5 1568.2 1569.7 1571.2 1572.5 1573.8 1575.5 1576.7 1577.9 1579.0 1580.2 1581.4 1582.4

4.32 4.30 4.28 4.26 4.24 4.22 4.21 4.19 4.17 4.16 4.14 4.13 4.11 4.10 4.09 4.07 4.06 4.05 4.04 4.03 4.02 4.01 4.00 3.99 3.98 3.97 3.96 3.95 3.95 3.94 3.93 3.93 3.92 3.91 3.91 3.90 3.90 3.89 3.89 3.88 3.88 3.87 3.87 3.87

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



58.7 58.7 58.6 58.5 58.4 58.2 58.1 57.9 57.7 57.4 57.2 56.9 56.7 56.4 56.0 55.7 55.3 55.0 54.6 54.2 53.8 53.3 52.9 52.4 51.9 51.4 50.9 50.4 49.9 49.3 48.8 48.2 47.6 47.0 46.4 45.8 45.2 44.6 43.9 43.3 42.6 41.9 41.3 40.6

ACCEPTED MANUSCRIPT 42

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.86 3.86 3.86 3.86 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.84 3.84 3.84 3.84 3.84 3.84 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.86 3.86 3.86 3.86 3.86 3.87 3.87 3.87

PT

1583.6 1584.4 1585.5 1586.1 1587.1 1587.7 1588.4 1589.0 1589.7 1590.0 1590.6 1591.3 1591.9 1592.2 1592.5 1592.9 1593.4 1593.7 1594.0 1594.3 1594.3 1594.7 1594.7 1594.7 1594.7 1595.0 1595.0 1595.0 1595.0 1594.7 1594.7 1594.3

RI

49 1545.5 4.22 47.5 1565.6 4.04 44.5 50 1546.7 4.22 46.9 1566.8 4.03 43.8 51 1547.8 4.21 46.2 1567.2 4.03 43.2 52 1548.7 4.21 45.6 1568.5 4.03 42.6 53 1549.3 4.21 45.0 1569.1 4.03 42.0 54 1549.9 4.20 44.5 1570.3 4.02 41.3 55 1550.5 4.20 43.9 1570.6 4.02 40.7 56 1551.8 4.20 43.4 1571.2 4.02 40.2 57 1552.7 4.20 42.9 1571.9 4.02 39.6 58 1553.3 4.19 42.4 1572.5 4.02 39.0 59 1553.9 4.19 42.0 1573.1 4.02 38.5 60 1554.2 4.19 41.5 1573.0 .01 37.9 61 1554.9 4.19 41.1 1573.6 4.01 37.4 62 1555.5 4.19 40.7 1574.2 4.01 36.9 63 1555.8 4.19 40.3 1574.9 4.01 36.4 64 1556.1 4.19 40.0 1575.5 4.01 35.9 65 1556.4 4.19 39.7 1575.8 4.01 35.4 66 1557.0 4.19 39.4 1576.1 4.02 35.0 67 1557.3 4.19 39.1 1576.4 4.02 34.5 68 1557.7 4.19 38.8 1576.4 4.02 34.1 69 1558.0 4.20 38.6 1576.7 4.02 33.7 70 1558.0 4.20 38.4 1577.0 4.02 33.3 71 1558.0 4.20 38.2 1577.3 4.02 32.9 72 1558.0 4.20 38.1 1577.3 4.02 32.5 73 1558.3 4.20 37.9 1577.3 4.03 32.2 74 1558.3 4.21 37.8 1577.3 4.03 31.9 75 1558.6 4.21 37.7 1577.6 4.03 31.5 76 1558.3 4.21 37.6 1577.6 4.03 31.2 77 1558.3 4.21 37.5 1577.3 4.04 31.0 78 1558.3 4.22 37.5 1577.3 4.04 30.7 79 1558.0 4.22 37.4 1577.3 4.04 30.4 80 1558.0 4.22 37.4 1577.0 4.04 30.2 5 Notation and units: 1 bar = 10 PaK - 273.15

39.9 39.2 38.5 37.8 37.1 36.4 35.7 35.0 34.3 33.5 32.8 32.1 31.4 30.6 29.9 29.2 28.5 27.8 27.0 26.3 25.6 24.9 24.2 23.5 22.8 22.1 21.5 20.8 20.1 19.5 18.8 18.2

ACCEPTED MANUSCRIPT 43 TABLE 5 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in potassium bromide solutions. uexp

0.1 mol.kg-1 KBr

4.61 4.59 4.55 4.53 4.51 4.50 4.46 4.45 4.43 4.41 4.40 4.39 4.37 4.35 4.34 4.32 4.31 4.29 4.28 4.27 4.25 4.24 4.23 4.22 4.21 4.20 4.19 4.18 4.17 4.16 4.15 4.14 4.14 4.13 4.12 4.12 4.11 4.10 4.09 4.09 4.08 4.08 4.07 4.07

MA

1442.4 1445.1 1452.7 1455.2 1458.4 1461.1 1466.7 1469.5 1472.2 1475.1 1477.9 1480.2 1483.2 1486.3 1488.8 1491.6 1494.7 1497.0 1499.6 1502.4 1505.0 1507.0 1509.3 1511.6 1513.9 1515.4 1518.0 1520.1 1522.1 1523.9 1525.3 1527.4 1529.1 1530.6 1532.0 1533.5 1535.3 1537.6 1539.4 1540.6 1541.5 1542.7 1543.9 1545.0

D

81.2 80.8 80.4 79.9 79.4 78.9 78.3 77.7 77.0 76.4 75.7 74.9 74.2 73.4 72.6 71.8 71.0 70.2 69.3 68.5 67.6 66.7 65.8 64.9 64.0 63.1 62.2 61.3 60.4 59.5 58.6 57.7 56.8 56.0 55.1 54.3 53.4 52.6 51.8 51.0 50.2 49.4 48.7 47.9

(∂CV/∂V)T

0.5 mol.kg-1 KBr

PT E

4.86 4.83 4.80 4.77 4.74 4.72 4.69 4.67 4.64 4.63 4.60 4.58 4.56 4.54 4.53 4.51 4.49 4.48 4.46 4.44 4.43 4.41 4.40 4.38 4.37 4.36 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.28 4.28 4.27 4.26 4.26 4.25 4.24 4.24 4.23 4.22 4.22

CE

1428.6 1433.1 1437.1 1441.4 1445.7 1449.7 1454.1 1457.1 1461.5 1464.5 1468.1 1471.8 1475.1 1478.5 1481.0 1484.7 1487.9 1490.2 1493.3 1495.6 1498.8 1501.4 1503.8 1506.8 1509.0 1511.1 1512.9 1515.2 1517.3 1519.1 1521.2 1523.3 1525.1 1526.9 1528.4 1530.2 1532.0 1533.2 1534.7 1535.9 1537.2 1539.0 1540.5 1541.1

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 KBr

72.9 72.4 71.9 71.3 70.8 70.2 69.6 69.1 68.5 67.9 67.3 66.7 66.0 65.4 64.8 64.1 63.5 62.8 62.2 61.5 60.8 60.2 59.5 58.8 58.1 57.4 56.7 56.1 55.4 54.7 54.0 53.3 52.6 51.9 51.3 50.6 49.9 49.3 48.6 47.9 47.3 46.7 46.0 45.4

1458.5 1461.4 1465.0 1468.3 1471.9 1475.2 1478.3 1481.4 1484.5 1487.5 1490.6 1493.2 1495.6 1498.0 1500.5 1503.0 1505.6 1507.8 1510.0 1512.4 1514.6 1516.6 1518.7 1520.6 1522.6 1524.4 1526.2 1528.2 1529.9 1531.7 1533.1 1534.6 1536.2 1537.4 1539.2 1540.1 1541.5 1542.5 1543.6 1544.8 1546.1 1547.1 1548.3 1549.3

4.34 4.33 4.30 4.29 4.27 4.25 4.23 4.21 4.20 4.18 4.17 4.15 4.14 4.13 4.11 4.10 4.09 4.08 4.07 4.06 4.05 4.04 4.03 4.02 4.01 4.00 3.99 3.98 3.98 3.97 3.96 3.96 3.95 3.95 3.94 3.94 3.93 3.93 3.92 3.92 3.91 3.91 3.91 3.90

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



62.1 61.9 61.6 61.4 61.1 60.7 60.4 60.0 59.7 59.3 58.8 58.4 58.0 57.5 57.0 56.5 56.0 55.5 55.0 54.4 53.9 53.3 52.7 52.2 51.6 51.0 50.4 49.8 49.2 48.6 48.0 47.4 46.7 46.1 45.5 44.9 44.3 43.6 43.0 42.4 41.8 41.2 40.6 40.0

ACCEPTED MANUSCRIPT 44

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.90 3.90 3.90 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.89 3.90 3.90 3.90 3.91 3.91 3.91 3.91 3.92

PT

1550.3 1551.2 1551.4 1552.4 1553.1 1553.6 1554.1 1555.0 1555.6 1556.2 1556.8 1557.1 1557.4 1557.7 1558.0 1558.6 1558.9 1559.2 1559.5 1559.5 1559.8 1560.1 1560.1 1560.4 1560.1 1560.1 1560.1 1560.1 1559.8 1559.8 1559.8 1559.5

RI

49 1542.4 4.22 47.2 1546.7 4.06 44.8 50 1543.6 4.21 46.5 1547.7 4.06 44.2 51 1544.2 4.21 45.8 1548.6 4.06 43.6 52 1545.1 4.21 45.2 1549.3 4.05 43.0 53 1546.7 4.20 44.5 1549.8 4.05 42.4 54 1547.6 4.20 43.9 1550.3 4.05 41.9 55 1548.2 4.20 43.3 1551.0 4.05 41.4 56 1549.1 4.19 42.7 1551.5 4.05 40.8 57 1549.9 4.19 42.2 1552.0 4.05 40.3 58 1550.4 4.19 41.7 1552.7 4.05 39.8 59 1551.0 4.19 41.2 1553.4 4.05 39.4 60 1551.6 4.19 40.7 1554.3 4.04 38.9 61 1551.9 4.19 40.2 1554.9 4.04 38.5 62 1552.9 4.19 39.8 1555.2 4.04 38.1 63 1553.2 4.19 39.4 1555.5 4.04 37.7 64 1553.7 4.19 39.0 1556.1 4.04 37.3 65 1554.1 4.19 38.6 1556.4 4.04 36.9 66 1554.4 4.19 38.3 1556.8 4.05 36.6 67 1554.7 4.19 37.9 1557.1 4.05 36.3 68 1555.1 4.19 37.6 1557.4 4.05 36.0 69 1555.4 4.19 37.4 1557.7 4.05 35.8 70 1555.4 4.19 37.1 1557.7 4.05 35.6 71 1555.7 4.19 36.9 1557.7 4.05 35.4 72 1555.7 4.20 36.7 1558.0 4.05 35.2 73 1555.7 4.20 36.5 1558.0 4.06 35.1 74 1555.7 4.20 36.3 1558.0 4.06 35.0 75 1555.7 4.20 36.1 1558.0 4.06 34.9 76 1556.0 4.20 36.0 1558.3 4.06 34.9 77 1555.7 4.21 35.9 1558.0 4.07 34.9 78 1555.7 4.21 35.8 1558.0 4.07 34.9 79 1555.7 4.21 35.7 1557.7 4.07 35.0 80 1555.4 4.22 35.6 1557.4 4.08 35.1 5 Notation and units: 1 bar = 10 PaK - 273.15

39.4 38.8 38.2 37.6 37.0 36.4 35.8 35.3 34.7 34.2 33.6 33.1 32.5 32.0 31.5 31.0 30.5 30.0 29.5 29.0 28.6 28.1 27.6 27.2 26.8 26.3 25.9 25.5 25.1 24.7 24.3 23.9

ACCEPTED MANUSCRIPT 45 TABLE 6 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in potassium iodide solutions. uexp

0.1 mol.kg-1 KI

4.55 4.53 4.49 4.47 4.45 4.44 4.40 4.39 4.36 4.34 4.33 4.31 4.29 4.28 4.26 4.25 4.23 4.22 4.21 4.19 4.18 4.17 4.16 4.15 4.14 4.13 4.12 4.11 4.10 4.09 4.08 4.08 4.07 4.06 4.05 4.05 4.04 4.03 4.03 4.02 4.02 4.02 4.01 4.01

MA

1439.4 1442.1 1449.7 1452.2 1455.4 1458.1 1463.7 1466.5 1471.7 1474.6 1477.6 1480.5 1483.3 1486.3 1488.9 1491.9 1494.9 1497.1 1499.6 1502.5 1504.8 1506.9 1509.2 1511.5 1513.7 1515.4 1517.8 1520.1 1521.7 1523.8 1525.4 1527.1 1529.0 1530.5 1532.0 1533.4 1534.9 1536.8 1538.3 1539.7 1540.7 1541.8 1542.8 1544.1

D

88.3 87.4 86.5 85.6 84.6 83.6 82.6 81.5 80.5 79.4 78.3 77.2 76.1 75.0 73.8 72.7 71.6 70.5 69.4 68.3 67.2 66.1 65.0 63.9 62.9 61.9 60.9 59.9 58.9 58.0 57.1 56.2 55.4 54.6 53.8 53.1 52.4 51.7 51.1 50.5 49.9 49.4 49.0 48.5

(∂CV/∂V)T

0.5 mol.kg-1 KI

PT E

4.84 4.81 4.78 4.76 4.73 4.70 4.67 4.66 4.63 4.61 4.59 4.57 4.55 4.53 4.51 4.49 4.47 4.46 4.44 4.43 4.41 4.40 4.39 4.37 4.36 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.28 4.27 4.26 4.25 4.25 4.24 4.23 4.23 4.22 4.22 4.21 4.21

CE

1428.6 1433.1 1437.1 1441.4 1445.7 1449.7 1454.1 1457.1 1461.5 1464.5 1468.1 1471.8 1475.1 1478.5 1481.0 1484.7 1487.9 1490.2 1493.3 1495.6 1498.8 1501.4 1503.8 1506.8 1509.0 1511.1 1512.9 1515.2 1517.3 1519.1 1521.2 1523.3 1525.1 1526.9 1528.4 1530.2 1532.0 1533.2 1534.7 1535.9 1537.2 1539.0 1540.5 1541.1

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 KI

72.0 71.6 71.1 70.7 70.2 69.7 69.2 68.7 68.1 67.6 67.0 66.4 65.8 65.2 64.5 63.9 63.3 62.6 61.9 61.2 60.5 59.8 59.1 58.4 57.7 57.0 56.3 55.6 54.9 54.1 53.4 52.7 52.0 51.2 50.5 49.8 49.1 48.4 47.7 47.0 46.3 45.6 44.9 44.3

1456.8 1459.7 1463.3 1466.7 1470.6 1474.0 1477.0 1480.3 1483.6 1486.6 1489.9 1492.6 1494.6 1497.0 1499.5 1502.0 1504.9 1506.8 1509.0 1511.8 1514.1 1516.1 1518.2 1520.1 1522.1 1524.0 1525.9 1528.0 1529.8 1531.7 1533.4 1534.8 1536.4 1537.6 1539.5 1540.5 1541.9 1542.6 1543.8 1545.0 1546.4 1547.6 1549.1 1550.3

4.22 4.20 4.18 4.16 4.14 4.13 4.11 4.09 4.08 4.06 4.04 4.03 4.02 4.01 4.00 3.98 3.97 3.96 3.95 3.94 3.93 3.92 3.91 3.90 3.89 3.88 3.88 3.87 3.86 3.85 3.84 3.84 3.83 3.83 3.82 3.82 3.81 3.81 3.81 3.80 3.80 3.79 3.79 3.78

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



59.5 60.2 60.9 61.4 61.9 62.4 62.7 63.0 63.2 63.3 63.4 63.4 63.3 63.2 63.0 62.8 62.4 62.1 61.6 61.1 60.5 59.9 59.2 58.5 57.7 56.8 55.9 54.9 53.9 52.8 51.6 50.4 49.2 47.9 46.5 45.1 43.7 42.2 40.6 39.0 37.3 35.6 33.9 32.1

ACCEPTED MANUSCRIPT 46

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.78 3.78 3.78 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.77 3.78 3.78 3.78 3.78 3.79 3.79 3.79 3.79

PT

1551.2 1552.2 1552.9 1553.9 1554.6 1555.1 1555.6 1556.5 1557.1 1557.7 1558.3 1558.6 1558.9 1559.2 1559.5 1560.1 1560.4 1560.7 1561.0 1561.0 1561.3 1561.6 1561.6 1561.9 1561.6 1561.6 1561.6 1561.6 1561.3 1561.3 1561.3 1561.0

RI

49 1542.4 4.20 48.1 1545.3 4.00 43.6 50 1543.6 4.20 47.8 1546.5 4.00 43.0 51 1544.2 4.20 47.5 1547.4 4.00 42.3 52 1545.1 4.19 47.2 1548.1 3.99 41.7 53 1546.7 4.19 47.0 1548.8 3.99 41.1 54 1547.6 4.18 46.8 1549.5 3.99 40.5 55 1548.2 4.18 46.7 1550.3 3.99 39.9 56 1549.1 4.18 46.6 1551.0 3.99 39.3 57 1549.9 4.18 46.5 1551.6 3.99 38.7 58 1550.4 4.18 46.5 1552.2 3.98 38.1 59 1551.0 4.18 46.6 1552.9 3.98 37.6 60 1551.6 4.18 46.6 1553.5 3.98 37.1 61 1551.9 4.18 46.8 1554.1 3.98 36.5 62 1552.9 4.17 46.9 1554.5 3.98 36.0 63 1553.2 4.17 47.1 1554.9 3.98 35.5 64 1553.7 4.17 47.3 1555.5 3.98 35.1 65 1554.1 4.17 47.6 1555.8 3.98 34.6 66 1554.4 4.17 47.9 1556.1 3.98 34.2 67 1554.7 4.17 48.3 1556.4 3.98 33.7 68 1555.1 4.18 48.6 1556.7 3.98 33.3 69 1555.4 4.18 49.0 1556.8 3.99 32.9 70 1555.4 4.18 49.5 1557.0 3.99 32.5 71 1555.7 4.18 49.9 1557.0 3.99 32.2 72 1555.7 4.18 50.4 1557.3 3.99 31.8 73 1555.7 4.18 50.9 1557.3 3.99 31.5 74 1555.7 4.19 51.5 1557.5 3.99 31.2 75 1555.7 4.19 52.0 1557.5 4.00 30.9 76 1556.0 4.19 52.6 1557.5 4.00 30.7 77 1555.7 4.20 53.2 1557.3 4.00 30.4 78 1555.7 4.20 53.8 1557.1 4.01 30.2 79 1555.7 4.20 54.4 1556.8 4.01 30.0 80 1555.4 4.21 55.1 1556.7 4.01 29.8 5 Notation and units: 1 bar = 10 PaK - 273.15

30.2 28.3 26.3 24.3 22.2 20.1 18.0 15.7 13.5 11.2 8.8 6.4 3.9 1.4 -1.2 -3.8 -6.5 -9.2 -12.0 -14.9 -17.8 -20.7 -23.8 -26.8 -30.0 -33.2 -36.4 -39.7 -43.1 -46.6 -50.1

ACCEPTED MANUSCRIPT 47 TABLE 7 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in rubidium chloride solutions. uexp

0.1 mol.kg-1 RbCl

4.60 4.57 4.55 4.53 4.51 4.48 4.46 4.44 4.42 4.41 4.39 4.37 4.35 4.34 4.32 4.30 4.29 4.27 4.26 4.25 4.23 4.22 4.21 4.20 4.19 4.18 4.17 4.16 4.15 4.14 4.13 4.12 4.12 4.11 4.10 4.10 4.09 4.09 4.08 4.07 4.07 4.07 4.06 4.06

MA

1443.5 1446.8 1450.5 1454.4 1458.3 1462.1 1465.4 1468.9 1472.3 1475.6 1478.7 1482.2 1485.0 1487.9 1491.0 1493.8 1496.6 1499.0 1501.2 1503.7 1506.5 1509.1 1511.4 1513.7 1515.7 1518.0 1520.2 1522.3 1524.0 1525.9 1527.8 1529.4 1531.3 1532.8 1534.3 1535.9 1537.4 1538.6 1540.1 1541.3 1542.7 1544.0 1545.1 1546.1

D

74.7 74.7 74.7 74.6 74.4 74.2 74.0 73.7 73.4 73.0 72.6 72.2 71.7 71.2 70.7 70.2 69.6 68.9 68.3 67.6 66.9 66.2 65.5 64.8 64.0 63.2 62.4 61.6 60.8 60.0 59.2 58.3 57.5 56.6 55.8 54.9 54.1 53.2 52.4 51.5 50.6 49.8 48.9 48.1

(∂CV/∂V)T

0.5 mol.kg-1 RbCl

PT E

4.84 4.81 4.79 4.76 4.74 4.71 4.69 4.67 4.64 4.62 4.60 4.58 4.56 4.54 4.53 4.51 4.49 4.48 4.46 4.45 4.43 4.42 4.40 4.39 4.38 4.37 4.36 4.35 4.33 4.33 4.32 4.31 4.30 4.29 4.28 4.28 4.27 4.26 4.26 4.25 4.24 4.24 4.23 4.23

CE

1430.9 1434.9 1438.9 1442.9 1447.0 1450.5 1454.6 1457.9 1461.6 1464.9 1468.0 1471.4 1474.8 1477.9 1480.7 1484.1 1486.7 1489.8 1492.4 1495.5 1497.8 1500.4 1502.8 1505.1 1507.4 1509.8 1512.1 1514.2 1516.3 1518.1 1519.8 1521.6 1523.4 1525.5 1527.0 1528.8 1530.0 1531.8 1533.0 1534.6 1535.8 1537.3 1538.5 1539.7

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 RbCl

75.9 75.5 75.0 74.4 73.8 73.2 72.5 71.8 71.0 70.2 69.4 68.6 67.8 66.9 66.0 65.2 64.3 63.4 62.5 61.6 60.7 59.8 59.0 58.1 57.3 56.4 55.6 54.8 54.1 53.3 52.6 51.9 51.2 50.6 50.0 49.4 48.8 48.3 47.8 47.4 46.9 46.5 46.2 45.8

1457.6 1460.7 1464.2 1467.8 1471.1 1474.8 1477.9 1481.3 1484.5 1487.5 1490.6 1493.4 1496.0 1498.6 1501.4 1504.1 1506.4 1508.9 1511.1 1513.3 1515.8 1518.1 1520.1 1522.4 1524.4 1526.1 1528.1 1529.8 1532.0 1533.5 1535.0 1536.8 1538.3 1540.2 1541.0 1542.5 1543.9 1545.2 1546.4 1547.7 1548.8 1550.0 1551.1 1552.0

4.34 4.32 4.30 4.28 4.26 4.24 4.22 4.20 4.19 4.17 4.15 4.14 4.12 4.11 4.10 4.08 4.07 4.06 4.05 4.04 4.03 4.02 4.01 4.00 3.99 3.98 3.97 3.96 3.95 3.95 3.94 3.93 3.93 3.92 3.91 3.91 3.90 3.90 3.89 3.89 3.89 3.88 3.88 3.87

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



63.1 62.9 62.7 62.5 62.2 62.0 61.7 61.3 61.0 60.6 60.2 59.8 59.4 59.0 58.5 58.0 57.5 57.0 56.5 55.9 55.4 54.8 54.3 53.7 53.1 52.5 51.8 51.2 50.6 49.9 49.3 48.7 48.0 47.3 46.7 46.0 45.3 44.7 44.0 43.3 42.6 41.9 41.3 40.6

ACCEPTED MANUSCRIPT 48

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.87 3.87 3.87 3.86 3.86 3.86 3.86 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.86 3.86 3.86 3.86 3.86 3.87 3.87 3.87 3.88 3.88

PT

1553.1 1554.0 1555.0 1556.0 1556.6 1557.5 1558.8 1559.5 1560.1 1560.4 1561.1 1561.3 1562.0 1562.6 1563.2 1563.5 1563.8 1564.1 1564.1 1564.5 1564.5 1564.8 1564.8 1564.8 1565.1 1564.8 1565.3 1565.0 1565.0 1564.6 1564.3 1564.0

RI

49 1540.6 4.23 47.2 1547.3 4.05 45.5 50 1541.9 4.22 46.4 1548.3 4.05 45.2 51 1542.5 4.22 45.5 1549.9 4.05 45.0 52 1543.4 4.21 44.7 1550.8 4.04 44.8 53 1544.0 4.21 43.9 1551.4 4.04 44.6 54 1544.9 4.21 43.1 1552.0 4.04 44.4 55 1545.9 4.21 42.2 1553.0 4.03 44.3 56 1546.8 4.20 41.4 1553.6 4.03 44.2 57 1547.7 4.20 40.6 1554.5 4.03 44.1 58 1548.3 4.20 39.8 1555.4 4.03 44.0 59 1548.9 4.20 39.0 1555.8 4.03 44.0 60 1549.6 4.20 38.2 1556.4 4.03 44.0 61 1550.2 4.20 37.5 1557.0 4.02 43.9 62 1550.8 4.20 36.7 1557.3 4.02 43.9 63 1551.4 4.20 35.9 1557.6 4.02 43.9 64 1551.7 4.20 35.2 1557.9 4.02 44.0 65 1552.0 4.20 34.4 1558.6 4.02 44.0 66 1552.3 4.20 33.7 1558.9 4.02 44.0 67 1552.7 4.20 32.9 1559.2 4.02 44.0 68 1552.7 4.20 32.2 1559.5 4.02 44.0 69 1553.0 4.20 31.4 1559.8 4.03 44.0 70 1553.3 4.20 30.7 1559.8 4.03 44.0 71 1553.3 4.20 30.0 1560.1 4.03 43.9 72 1553.6 4.21 29.2 1559.8 4.03 43.9 73 1553.9 4.21 28.5 1559.8 4.04 43.8 74 1553.6 4.21 27.8 1559.5 4.04 43.7 75 1553.3 4.21 27.0 1560.5 4.04 43.5 76 1553.3 4.22 26.3 1560.2 4.05 43.3 77 1552.9 4.22 25.6 1559.9 4.05 43.1 78 1552.7 4.22 24.8 1559.6 4.06 42.8 79 1552.3 4.23 24.1 1559.2 4.07 42.4 80 1552.0 4.23 23.3 1559.0 4.08 42.0 5 Notation and units: 1 bar = 10 PaK - 273.15

39.9 39.2 38.5 37.8 37.2 36.5 35.8 35.1 34.5 33.8 33.1 32.5 31.8 31.1 30.5 29.8 29.2 28.5 27.9 27.2 26.6 26.0 25.3 24.7 24.1 23.4 22.8 22.2 21.5 20.9 20.3 19.6

ACCEPTED MANUSCRIPT 49 TABLE 8 Experimental sound velocities uexp, isentropic compressibility coefficients S and (∂CV/∂V)T values in rubidium iodide solutions. uexp

0.1 mol.kg-1 RbI

4.64 4.61 4.59 4.57 4.54 4.52 4.50 4.48 4.46 4.44 4.43 4.41 4.39 4.38 4.36 4.35 4.33 4.32 4.31 4.29 4.28 4.27 4.26 4.25 4.24 4.23 4.22 4.21 4.20 4.19 4.18 4.18 4.17 4.16 4.16 4.15 4.14 4.14 4.13 4.13 4.12 4.12 4.11 4.11

MA

1412.8 1416.6 1420.5 1423.9 1427.7 1431.1 1434.8 1438.2 1441.3 1444.5 1447.4 1450.6 1453.6 1456.2 1458.9 1461.7 1464.4 1467.1 1469.3 1471.8 1474.2 1476.6 1478.2 1480.2 1482.1 1484.2 1486.1 1488.0 1489.8 1491.7 1493.0 1494.7 1496.2 1498.1 1499.3 1501.1 1502.5 1503.7 1505.2 1506.3 1507.5 1508.7 1509.8 1510.7

D

83.3 82.4 81.4 80.4 79.4 78.4 77.3 76.3 75.3 74.2 73.2 72.2 71.2 70.1 69.1 68.1 67.2 66.2 65.2 64.3 63.4 62.5 61.6 60.8 60.0 59.2 58.4 57.7 57.0 56.4 55.7 55.1 54.6 54.1 53.6 53.2 52.8 52.4 52.1 51.9 51.7 51.5 51.3 51.3

(∂CV/∂V)T

0.5 mol.kg-1 RbI

PT E

4.85 4.83 4.80 4.77 4.74 4.72 4.70 4.67 4.65 4.63 4.61 4.59 4.57 4.55 4.53 4.51 4.50 4.48 4.47 4.45 4.44 4.42 4.41 4.40 4.38 4.37 4.36 4.35 4.34 4.33 4.32 4.31 4.30 4.29 4.29 4.28 4.27 4.26 4.26 4.25 4.25 4.24 4.24 4.23

CE

1424.1 1427.4 1432.2 1436.5 1440.0 1443.8 1447.9 1451.6 1455.1 1458.7 1461.8 1465.3 1468.5 1471.8 1475.0 1477.7 1480.9 1483.7 1486.4 1489.2 1492.0 1494.6 1496.9 1499.4 1501.6 1504.0 1506.1 1508.1 1510.2 1512.2 1514.2 1516.0 1517.9 1519.4 1521.3 1522.9 1524.4 1526.0 1527.4 1528.7 1530.0 1531.4 1532.6 1533.8

AC

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

S

uexp

S

(∂CV/∂V)T

1.0 mol.kg-1 RbI

90.9 88.7 86.4 84.1 81.8 79.5 77.2 74.9 72.6 70.3 68.1 66.0 63.9 61.8 59.9 58.0 56.2 54.5 52.9 51.3 49.9 48.7 47.5 46.4 45.5 44.7 44.0 43.5 43.1 42.9 42.8 42.8 43.0 43.3 43.8 44.4 45.2 46.1 47.1 48.3 49.7 51.1 52.7 54.4

1403.5 1406.3 1409.5 1412.3 1416.0 1418.6 1421.6 1424.8 1427.7 1430.4 1433.2 1435.6 1438.4 1440.7 1442.9 1444.9 1447.2 1449.8 1451.8 1454.1 1456.1 1457.9 1459.7 1461.5 1463.4 1465.2 1466.7 1468.6 1469.6 1471.7 1473.1 1474.8 1475.9 1477.6 1478.7 1480.1 1481.8 1482.4 1483.5 1484.6 1485.8 1486.6 1487.8 1488.3

4.41 4.39 4.36 4.34 4.32 4.30 4.28 4.26 4.25 4.23 4.22 4.21 4.19 4.18 4.17 4.16 4.15 4.14 4.13 4.12 4.11 4.10 4.09 4.09 4.08 4.07 4.06 4.05 4.05 4.04 4.03 4.02 4.02 4.01 4.00 4.00 3.99 3.98 3.98 3.97 3.97 3.96 3.96 3.96

PT

(∂CV/∂V)T

RI

S

SC

uexp

NU



73.6 71.6 69.7 67.9 66.3 64.8 63.4 62.0 60.8 59.7 58.6 57.6 56.7 55.8 55.0 54.2 53.5 52.8 52.2 51.5 50.9 50.4 49.8 49.2 48.7 48.2 47.6 47.1 46.6 46.0 45.5 44.9 44.4 43.8 43.3 42.7 42.1 41.5 40.9 40.4 39.8 39.2 38.6 38.0

ACCEPTED MANUSCRIPT 50

SC

NU

MA

D

PT E

CE

AC

uexp./m.s-1 ; S = S 105 /bar-1; (∂CV/∂V)T /bar.K-1.

3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.95 3.96 3.96 3.96 3.96 3.97 3.97 3.97 3.97 3.98 3.98 3.98 3.98 3.98 3.97 3.97 3.96 3.95 3.94 3.93 3.92

PT

1489.2 1490.1 1490.6 1491.2 1491.8 1492.3 1493.2 1493.8 1494.4 1494.9 1495.5 1495.9 1496.2 1496.8 1497.1 1497.4 1497.6 1497.9 1497.9 1498.2 1498.2 1498.5 1498.5 1498.5 1498.8 1498.5 1498.5 1498.2 1497.9 1497.6 1497.4 1497.1

RI

49 1534.9 4.23 51.2 1511.9 4.11 56.3 50 1536.0 4.22 51.2 1512.8 4.10 58.2 51 1536.8 4.22 51.3 1513.7 4.10 60.3 52 1537.9 4.22 51.4 1514.3 4.10 62.5 53 1538.8 4.21 51.5 1515.7 4.10 64.7 54 1539.4 4.21 51.7 1516.6 4.09 67.1 55 1540.3 4.21 51.9 1517.2 4.09 69.5 56 1541.2 4.21 52.2 1517.5 4.09 72.1 57 1541.8 4.21 52.5 1518.1 4.09 74.6 58 1542.5 4.20 52.9 1518.7 4.09 77.3 59 1543.1 4.20 53.3 1519.3 4.09 80.0 60 1543.4 4.20 53.7 1519.9 4.09 82.7 61 1544.0 4.20 54.2 1520.5 4.09 85.5 62 1544.6 4.20 54.7 1520.8 4.09 88.3 63 1544.9 4.20 55.3 1521.1 4.09 91.0 64 1545.2 4.20 55.9 1521.4 4.09 93.8 65 1545.5 4.20 56.5 1521.7 4.09 96.6 66 1546.1 4.20 57.2 1522.0 4.09 99.3 67 1546.4 4.21 57.9 1522.3 4.09 101.9 68 1546.8 4.21 58.6 1522.6 4.09 104.5 69 1546.8 4.21 59.4 1522.6 4.09 107.1 70 1546.8 4.21 60.2 1522.9 4.10 109.5 71 1546.8 4.21 61.0 1522.9 4.10 111.8 72 1547.1 4.22 61.9 1522.9 4.10 113.9 73 1547.1 4.22 62.8 1522.9 4.10 116.0 74 1546.8 4.22 63.7 1522.9 4.11 117.8 75 1546.8 4.22 64.6 1523.2 4.11 119.5 76 1546.8 4.23 65.5 1522.9 4.12 121.0 77 1546.8 4.23 66.5 1522.9 4.12 122.2 78 1546.5 4.23 67.4 1522.9 4.12 123.2 79 1546.1 4.23 68.4 1522.6 4.13 123.9 80 1545.8 4.24 69.4 1522.3 4.13 124.3 5 Notation and units: 1 bar = 10 PaK - 273.15

37.5 36.9 36.4 35.9 35.4 34.9 34.5 34.1 33.8 33.6 33.4 33.3 33.2 33.3 33.5 33.7 34.1 34.6 35.3 36.1 37.1 38.3 39.6 41.2 43.0 45.0 47.3 49.8 52.6 55.7 59.1 62.9

ACCEPTED MANUSCRIPT 51

1.0

0.0

PT

 u1/ms

-1

0.5

-1.0 0

20

40

60

80

NU



SC

RI

-0.5

Figure 1. Deviations of sound velocity in pure water from the Marczak equation as a

MA

function of dimensionless temperature  = T/K - 273.15.

. ,  - experiments with SAM equipment; . ,  - experiments with Optel

AC

CE

PT E

D

equipment;

ACCEPTED MANUSCRIPT 52

1600

NaBr

1550

H2O NaI

PT

1500

RI

u(T;m)/ms

-1

NaCl

0

20

40

60

80

NU



SC

1450

MA

Figure 2. Sound velocities u(T,m) in pure water and in 1.0 mol.kg-1 sodium chloride, sodium bromide and sodium iodide solutions as a function of dimensionless

AC

CE

PT E

D

temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 53

NaI

T 4.2

PT

10

T ,S 10 / Pa

-1

4.4

NaBr 4.0

NaCl

3.8 20

40

NU

0

SC

RI

S

60

80



MA

Figure 3. The isothermal compressibility coefficients T(T;m). and the isentropic compressibility coefficients S.(T;m) of 1.0 mol.kg-1 sodium chloride, sodium bromide

D

and sodium iodide solutions (T(T;m). > S.(T;m)) as a function of dimensionless

AC

CE

PT E

temperature  = T/K -273.15.

ACCEPTED MANUSCRIPT 54

0.5

0.1 m

NaCl

3

f(T;m)/cm K

-1

0.0

1.0 m -0.5

PT

0.5 m

-1.5 0

20

40

60

80

NU



SC

RI

-1.0

MA

Figure 4. Differences in the change of molar heat capacities with pressure f(T;m) = [-(∂CP/∂P)T,m] of sodium chloride 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1

AC

CE

PT E

D

solutions as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 55

10

NaCl

0.1 m

PT

0.5 m -10

RI

g(T;m)/barK

-1

0

1.0 m

0

20

40

60

80

NU



SC

-20

MA

Figure 5. Differences in the change of molar heat capacities with volume g(T;m) = [(∂CV/∂V)T,m] of sodium chloride 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions

AC

CE

PT E

D

as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 56

1.5

NaBr

3

f(T;m)/cm K

-1

1.0

0.5

PT

NaCl

RI

0.0

-0.5 0

20

40

60

80

NU



SC

NaI

Figure 6. Differences in the change of molar heat capacities with pressure f(T;m) =

MA

[-(∂CP/∂P)T,m] of 0.1 mol.kg-1 solutions of sodium chloride, sodium bromide and

AC

CE

PT E

D

sodium iodide as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 57

10.0

5.0

PT

0.0

-5.0

RI

g(T;m)/barK

-1

NaCl NaBr

-10.0 0

20

40

Figure 7.

60

80

NU



SC

NaI

Differences in the change of molar heat capacities with volume g(T;m) =

MA

[(∂CV/∂V)T,m] of 0.1 mol.kg-1 solutions of sodium chloride, sodium bromide and

AC

CE

PT E

D

sodium iodide as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 58

h(T;m)

10.0

PT

NaI NaBr 8.0

6.0 0

20

40

60

80

NU



SC

RI

NaCl

MA

Figure 8 Hydration numbers h(T;m) of 1.0 mol.kg-1 solutions of sodium chloride, sodium bromide and sodium iodide as a function of dimensionless temperature  =

AC

CE

PT E

D

T/K - 273.15.

ACCEPTED MANUSCRIPT 59

4.8

KCl 0.1 m

4.4

PT

0.5 m

10

S ,  /Pa

-1

4.6

RI

4.2

SC

4.0

NU

3.8 40

20

0

60

1.0 m 80

MA



Figure 9. The isothermal compressibility coefficients T. and the isentropic compressibility coefficients S. of 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1

D

potassium chloride solutions (T(T;m). > S.(T;m)) as a function of dimensionless

AC

CE

PT E

temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 60

15

KBr

PT RI

9

6

H2O

SC

V(T;m)/barK

-1

12

NU

3

0 0

20

40

60

80

MA



Figure 10. The isochoric thermal pressure coefficients V(T;m) of pure water (red

D

curve) and 0.1 mol.kg-1(topaz curve), 0.5 mol.kg-1 (blue curve) and 1.0 mol.kg-1

AC

CE

 = T/K - 273.15.

PT E

potassium bromide (green curve) solutions as a function of dimensionless temperature

ACCEPTED MANUSCRIPT 61

2.0

KBr

1.0

KCl

RI

PT

3

 f(T;m) /cm K

-1

KI

SC

0.0

0

NU

-1.0 20

40

60

80

MA



Figure 11. Differences in the change of molar heat capacities with pressure f(T;m)

D

= [-(∂CP/∂P)T,m] of potassium chloride, potassium bromide, potassium iodide 0.1

PT E

mol.kg-1 solutions (three upper curves) and 0.5 mol.kg-1 solutions (three lower curves)

AC

CE

as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 62

10.0

5.0

KI

0.0

PT

KBr

-5.0

RI

 g(T;m) / barK

-1

KCl

SC

-10.0

0

NU

-15.0 20

40

60

80



MA

Figure 12. Differences in the change of molar heat capacities with volume g(T;m) = [(∂CV/∂V)T,m] of potassium chloride, potassium bromide, potassium iodide 0.1

D

mol.kg-1 solutions (three upper curves) and 0.5 mol.kg-1 solutions (three lower curves)

AC

CE

PT E

as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 63

15

KI

PT

h(T;m)

12

KBr

SC

RI

9

KCl

NU

6 40

20

0

60

80

MA



Figure 13 Hydration numbers h(T;m) of sodium chloride, sodium bromide and sodium iodide 0.5 mol.kg-1 solutions (upper curves) and 1.0 mol.kg-1 solutions (lower

AC

CE

PT E

D

curves) as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 64

1.6

13

(T;m) 10 /s

1.2

RI

PT

0.8

0.4

SC

KCl

NU

0.0

40

20

0

60

NaCl

80

MA



Figure 14. Differences between the ultrasonic relaxation times of water and those of

D

solutions (T;m) = [(T;0) - (T;m)]. as a function of concentration m and

PT E

dimensionless temperature  = T/K - 273.15. Red curves are 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions of sodium chloride and blue curves are 0.1 mol.kg-1, 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions of

AC

CE

potassium chloride

ACCEPTED MANUSCRIPT 65

18.0

PT

15.0

12.0

RI

KBr 9.0

SC

H*, TS* / kJmol

-1

KCl

KI

6.0 20

40

NU

0

60

80



MA

Figure 15. The change of enthalpy H*(T;m) (three upper curves) and entropy TS*(T;m) of activation (three lower curves) in 1.0 mol.kg-1 solutions of potassium

D

chloride, potassium bromide and potassium iodide as a function of dimensionless

AC

CE

PT E

temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 66

2.0

PT

3

 f(T;m) / cm K

-1

RbI, 0.1 m 1.0

RbCl, 0.1 m

RI

0.0

RbCl, 1.0 m

SC

RbI, 1.0 m

NU

-1.0

40

20

0

60

80

MA



D

Figure 16. Differences in the change of molar heat capacities with pressure f(T;m) = [-(∂CP/∂P)T,m] of rubidium chloride and rubidium iodide 0.1 mol.kg-1 and 1.0

AC

CE

PT E

mol.kg-1 solutions as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 67

20

RbI, 0.1 m

PT

RbCl, 0.1 m

RI

0

RbCl, 1.0 m -10

SC

 g(T;m) /barK

-1

10

RbI, 1.0 m

0

NU

-20 20

40

60

80

MA



Figure 17. Differences in the change of molar heat capacities with volume g(T;m) =

D

[(∂CV/∂V)T,m] of rubidium chloride and rubidium iodide 0.1 mol.kg-1 and 1.0 mol.kg-1

AC

CE

PT E

solutions as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 68

14

RbI, 0.5 m

h(T;m)

12

PT

RbI, 1.0 m

RbCl, 0.5 m

RbCl, 1.0 m RbCl, 1.0 m

8 20

40

NU

0

SC

RI

10

60

80



MA

Figure 18 Hydration numbers h(T;m) of rubidium chloride and rubidium iodide 0.5 mol.kg-1 and 1.0 mol.kg-1 solutions as a function of dimensionless temperature  =

AC

CE

PT E

D

T/K - 273.15.

ACCEPTED MANUSCRIPT 69

PT

16.0

H2O

RI

RbI

SC

8.0

NU

H*, TS*, G* / kJmol

-1

24.0

0.0

40

20

0

60

RbCl

80

MA



Figure 19. The change of enthalpy H*(T;m) , entropy TS*(T;m) and free Gibbs

D

energy G*(T;m) of activation in pure water, and in 0.5 mol.kg-1 solutions of

PT E

rubidium chloride and rubidium iodide (H*(T;m) > TS*(T;m) >> G*(T;m)) as a

AC

CE

function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 70

RI

10

PT

4.2

S(T;m)10 /Pa

-1

4.4

NU

SC

4.0

3.8 0

20

40

60

80

MA



Figure 20. The isentropic compressibility coefficients S.(T;m) of pure water and of

D

1.0 mol.kg-1 alkali metal chloride solutions as a function of dimensionless temperature

PT E

 = T/K -273.15.

AC

CE

 - H2O;  - LiCl [66];  - NaCl;  - KCl;  - RbCl;  - CsCl [28].

ACCEPTED MANUSCRIPT 71

PT

4.5

RI

10

S(T;m)10 /Pa

-1

5.0

NU

SC

4.0

40

20

0

60

80

MA



Figure 21. The isentropic compressibility coefficients S.(T;m) of pure water and of 1.0 mol.kg-1 alkali metal bromides and iodides solutions as a function of

D

dimensionless temperature  = T/K -273.15.

AC

CE

PT E

 - H2O;  - NaBr;  - KBr;  - NaI;  - KI;  - RbI.

ACCEPTED MANUSCRIPT 72

14

12

KI

10

PT

h(T;m)

NaI

RbI

RI

KBr

0

20

40

NU



SC

8

60

NaBr 80

Figure 22 Hydration numbers h(T;m) of 1.0 mol.kg-1 solutions of alkali metal

AC

CE

PT E

D

MA

bromides and iodides as a function of dimensionless temperature  = T/K - 273.15.

ACCEPTED MANUSCRIPT 73

Graphical Abstract

1.0

RI

0.0

SC

 u1/ms

-1

PT

0.5

NU

-0.5

0

20

40

MA

-1.0

AC

CE

PT E

D



60

80

ACCEPTED MANUSCRIPT 74

Highlights Compressibilities of eight alkali metal halide solutions were determined as a function of m and T

From sound velocities and densities, a number of thermodynamic parameters

PT

were evaluated.

RI

First and second derivatives of V and P with respect to T indicated changes in

SC

structure of water.

At room T alkali metal halides destroy water structure, at high T they are

CE

PT E

D

MA

NU

structure-making solutes.

AC

.