Heat of Solution and Dilution

The heat of solution is the enthalpy change associated with the addition of a specified amount of solute to a specified amount of solvent at constant temperature and pressure. For convenience we shall use water as the solvent in the illustrations, but the argument can be applied to any solvent with slight modification. The change in state is represented by 

One mole of solute X is added to n moles of water. The water is given the symbol Aq in this equation it is convenient to assign a conventional enthalpy of zero to the water in these solution reactions. 

The values of AH show the general dependence of the heat of solution on the amount of solvent. As more and more solvent is used, the heat of solution approaches a limiting 

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Heats of Solution and Dilution of Lithium Perchlorate in Aqueous Acetonitrile... 

The heats of solution and dilution of electrolytes in nonaqueous-aqueous solvent mixtures have been limited mostly to alcohol-water systems and a few measurements in dimethylsulfoxide-water and dioxane-water mixtures (J, 2). The structural maximum in aqueous-organic solvents at high water content has been well established by a variety of techniques (3,4), but few systems have been explored over the whole composition range. 

The purpose of this study is to examine the structural features of acetonitrile-water mixtures over the whole composition range using the heats of solution and dilution of lithium perchlorate as a probe. The effect of water on thermodynamic properties such as heats of solution is also of interest. 

The molar differential heats of solution and dilution are examples of partial molar quantities, which are of such importance that they must... 

The theory of Isotope effects In condensed phase systems, especially vapor pressure Isotope effects (VPIE) Is briefly reviewed. It Is pointed out that the VFIE can be enqtloyed as one measure of the effect of Intermolecular forces on the motions of molecules In condensed phases. This Is Illustrated with a number of examples from the recent literature and from our own laboratory. A more detailed description of our recent work on thermodynamic solvent Isotope effects In aqueous systems Is presented. Experiments on vapor pressures, freezing points, and heats of solution and dilution of solutions of electrolytes In HOH and DOD are described. Implications are discussed with respect to the aqueous solvent structure problem. 

Chemical thermodynamics was developed by Pierre Maurice Martin Duhem (Paris, lo June i86i-Cabrespine, 14 September 1916), professor of theoretical physics in Bordeaux, who published on the equations for heats of solution and dilution which had been deduced by Kirchhoff, on the liquefaction of gaseous mixtures, eutectic and transition points for binary mixtures which can form mixed crystals, and a long series of papers on false equilibrium of doubtful value. He published some books on thermodynamics and later on the history of science. An important general thermodynamic equation (Gibbs-Duhem equation) was deduced independently by Gibbs and Duhem. ... 

Heats of solution and dilution, Asoi7/y and A hHy, respectively, are determined with the help of calorimetric measurements. According to Fig. 1 and Eqs. (45) the following relationships can be written ... 

Tabulated are the equivalent conductances, transference numbers, activity coefficients, densities and partial molar volumes, apparent molar compressibilities, heats of solution and dilution for the rare earth salts in aqueous solution at 25 "C. 

MA2 Maron, S.H. and Fihsko, F.E., Heats of solution and dilution for polyethylene oxide in... 

TAG Tager, A.A. and Podlesnyak, A.I., Concentrated polymer solutions. I. Determination of the integral and differential heats of solution and dilution of polyisobutylene and polystyrene (Russ.), Vysokomol. Soedin., Ser. A, 5, 87, 1963. 

A. N. Campbell and 0. N. Bhatnagar, Can. J. Chem., 50, 1627 (1972). Some thermodynamic properties of lithium chlorate in water and water-dioxane mixtures. Heats of solution and dilution. 

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