Volume changes on solvation

When a solute is added to a solvent, e.g. an electrolyte to water, it might be expected that the final volume of the solution would be greater then the volume of the solvent used. However, this is not always the case, and large negative changes in volume are often found experimentally. These are found by measuring the density of solutions as a function of concentration of the electrolyte. 

Analogous interpretations to the entropy data can be given for changes in volume on solution of an electrolyte, though the effects are less definite than with the entropies. 

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