New thermodynamic data for KNO3-sucrose-water ternary system: Water activity, osmotic coefficient, activity coefficient, excess Gibbs energy, solubility and transfer Gibbs energy at 298.15 K

Abstract

On the basis of the measurement of relative humidity, the hygrometric method is used to determine the new thermodynamic data of water activity and osmotic coefficient of water-sucrose-potassium nitrate system in the wide range of KNO3 molality, varying from 0.10 to 3.00 mol kg−1 and for various contents of sucrose (0.10, 0.30, 0.5, 1.00, 2.00, 4.00, and 6.00 mol kg−1). The experimental results are compared with the predictions of the extended composed additivity (ECA) rule, the Lin et al. equation, and Lietzke and Stoughton (LS II) models. The Pitzer-Simonson-Clegg model is employed to correlate these data and calculate the other thermodynamic properties such as, the stoichiometric ionic mean activity coefficient of KNO3, the excess Gibbs energy, the solubility in aqueous solution of the studied system and the transfer Gibbs energy of KNO3 from water (W) to sucrose-water (W + S) mixtures. The different interactions that occur in the ternary solution between water, sucrose and KNO3 are discussed.