抄録
Using a derivatograph, the temperatures and heats of decomposition of MnO2 and Mn2O3 as well as the temperature and heat of transformation of Mn3O4 have been studied. Using CaCO3 as standard, the heat of decomposition of MnO2 to Mn2O3 has been determined to be 25.56±1.67 kJ/mol of MnO2, and that of decomposition of Mn2O3 to Mn3O4 to be 15.94±2.09 kJ/mol of Mn2O3. The temperatures of decomposition of MnO2 and Mn2O3 to lower oxides, namely, Mn2O3 and Mn3O4 respectively, have been found to be 843±5 K and 1263±5 K respectively under atmospheric conditions. It has been confirmed that Mn3O4 undergoes a crystalline transformation during cooling at 1453±5 K with 4.35±0.04 kJ/mol of Mn3O4 as the heat of transformation.
