Specific heat of sodium nitrate and silver nitrate by medium high temperature adiabatic calorimetry

Abstract

��� A relatively simple adiabatic calorimeter for use in the temperature range 50-350� was constructed and used to measure the specific heat of sodium nitrate from 150 to 300� and silver nitrate from 70 to 250�. Each salt undergoes a solid-solid and a solid-liquid transformation in these temperature ranges. The Cp values for sodium nitrate agreed within the calculated experimental error of �0.2% with those of Sokolov and Shmidt1 but the silver nitrate showed a large discrepancy with those of Janz and Kelly2 obtained by drop calorimetry for the 160-210� region, where thermal hysteresis may have occurred in the drop calorimetric technique. The heat of transformation for the solid-solid transition in silver nitrate at 159.4� was found to be 561�4 cal mole-1.