Heat capacities of NaNO3 and KNO3 from 350 to 800 K

Abstract The heat capacities of NaNO 3 and KNO 3 were determined from 350 to 800 K by differential scanning calorimetry. Solid-solid transitions and melting were observed at 550 and 583 K for NaNO 3 and 406 and 612 K for KNO 3 , respectively. The entropies associated with the solid-solid transitions were measured to be (8.43± 0.25) J K −1 mole −1 for NaNO 3 and (13.8±0.4) J K −1 mole −1 for KNO 3 . At 298.15 K the values of C 0 P S 0 P , { H 0 ( T )- H 0 (0)}/ T and -{ G 0 ( T )- H 0 (0)}/ T , respectively, are 91.94, 116.3, 57.73, and 58.55 J K −1 mole −1 for NaNO 3 and 95.39, 133.0, 62.93, and 70.02 J K −1 mole −1 for KNO 3 . Values for S 0 T , { H 0 ( T )- H 0 (0)}/ T , and -{ G 0 ( T )- H 0 (0)}/ T were calculated and tabulated from 15 to 800 K for NaNO 3 and KNO 3 .