A comparative study of partial molar volumes of some hydrated and anhydrous salts of transition metal sulphates and magnesium sulphate in water at different temperatures

摘要

Partial molar volumes of some hydrated and anhydrous salts of transition metal sulphates,viz.,cobalt sulphate,nickel sulphate copper sulphate,zinc sulphate and magnesium sulphate have been determined in water at five equidistant temperatures(298.15,303.15,308.15,313.15 and 318.15 K).The density data have been analysed by means of Mason's equation.The partial molar volumes(phi_v~o)and experimental slopes(S*_v)have been interpreted in terms of ion-solvent and ion-ion interactions,respectively.The partial molar volumes vary with temperature as a power series of temperature.Structure-making/breaking capacities of hydrated and anhydrous salts have been inferred from the sign of i.e.,the second derivative of partial molar volume with respect to temperature at constant pressure.The hydrated salts act as structure makers while anhydrous salts act as structure breakers in water,i.e.,the behaviour is reversed on removal of water of crystallization.