THERMODYNAMIC PROPERTIES OF HIGH-TEMPERATURE AQUEOUS SOLUTIONS .11. CALORIMETRIC DETERMINATION OF STANDARD PARTIAL MOLAL HEAT CAPACITY AND ENTROPY OF SODIUM CHLORIDE SOLUTIONS FROM 100 DEGREES TO 200 DEGREES

A high-pressure twin solution calorimeter utilizing thermistors as temperature sensing elements was used to make heat of solution measurements of NaCl in water from 100 to 200°. From these and previous literature data the standard partial molal heat capacities and entropies of NaCl (aq) were calculated between 0 and 200°. The observed entropies showed good agreement with values predicted by a correspondence principle previously developed in these laboratories. An analysis of the Born free energy of hydration of aqueous ions at different temperatures indicates only qualitative agreement with the experimental data.