Thermodynamic properties of potassium nitrate–magnesium nitrate compound [2KNO3·Mg(NO3)2]

The Mg(NO3)2–KNO3 binary system phase diagram has a congruent melting compound, 2KNO3·Mg(NO3)2. The thermodynamic properties for this compound are not available in the literature. In this study, the nitrate compound was synthesized and the melting point and heat capacity were determined using differential scanning calorimetry (DSC). Two endothermic peaks were observed at 404.8 K and 468.83 K corresponding to solid state transition and melting of the compound with the enthalpies of transitions as 2.71 kJ/mol and 20.73 kJ/mol, respectively. The heat capacity data as function of temperature are fit to polynomial function and thermodynamic properties like enthalpy, entropy and Gibbs energies of the compound as function of temperature are subsequently deduced.

► Thermodynamic properties of 2KNO3·Mg(NO3)2 compound were experimentally determined.
► The 2KNO3·Mg(NO3)2 compound melting point and heat capacity were determined.
► The enthalpies of transitions were determined.
► The enthalpy, entropy and Gibbs energies as function of temperature were reduced.