An Investigation on the System K₂Cr₂O₇ — KNO₃ by DSC

Abstract

The phase diagram of the binary system K₂Cr₂O₇-KNO₃ has been reinvestigated using DSC. The system is a simple eutectic one, with the eutectic point at 80 mole% KNO + 20 mole% K₂Cr₂O₇ and 542.8 K. The enthalpies of fusion and the heat capacities of both K₂Cr₂O₇ and KNO₃ have been redetermined, as well as the enthalpy of fusion of the eutectic mixture. The following results have been obtained:

• ΔH_f(K₂Cr₂O₇): 40.39 ± 0.28 KJ/mole

• ΔH_f(KNO₃): 9.89 ± 0.09 KJ/mole

• ΔH_f(eut): 14.35 ± 0.09 KJ/mole mixture.