Volumetric and thermal properties of some aqueous electrolyte solutions

Precise densities of potassium bromide (0.10014, 0.49997, and 0.99962 mol kg−1) and potassium iodide (0.10008, 0.50551, and 0.99993 mol kg−1) aqueous solutions were determined at 1-K temperature intervals from T=278.15 to T=338.15 K, and they are compared with the literature data. Measured densities were expressed as polynomials of temperature, and these polynomials were used in an evaluation of the apparent molar volumes, the cubic expansion coefficients, the apparent molar expansibilities, and the second derivatives of volume with respect to temperature, which are interrelated with the derivatives of isobaric heat capacities with respect to pressure. In the framework of changes in the structure of water, these derivatives are discussed for potassium bromide and potassium iodide solutions.