Thermal studies on the phase transitions in sodium nitrite

Abstract The phase transitions in sodium nitrite have been studied by differential scanning calorimetry. Two reversible phase transitions were observed at 436.1 ±1.1 and 437.3 ± 1.3 K having Δ H values upon heating of about 249 ± 5 and 27 ± 3 J mol −1 and Δ S values of 0.60 ±0.01 and 0.06 ± 0.01 J mol −1 ' K −1 , respectively. Both transitions exhibit thermal hysteresis.