Enthalpy increment measurements of NaCrO 2 using a high temperature Calvet calorimeter

Abstract

Enthalpy increment measurements on NaCrO 2(s) were carried out in the temperature range 323 to 839 K using a high temperature Calvet micro calorimeter. The enthalpy increment values were least-squares fitted with temperature with the constraint that (H T 0 − H 298 0) at 298.15 K equals zero and can be given by: ( H T 0 − H 298 0)( J/ mol) ± 336 = −23515 + 75.364 T( K) + 0.01256 T 2( K) (323 to 839 K). The first differential of the above equation with temperature gives the constant pressure molar beat capacity of NaCrO 2(s), which is given by: C p 0( NaCrO 2, s, T)( J/ K mol) = 75.364 + 0.02512 T( K). The thermal properties of NaCrO 2(s) were calculated using the molar heat capacities from the present study and S 0(298 K) from the literature.