Standard gibbs energy of formation of Mg48Zn52 determined by solution calorimetry and measurement of heat capacity from near absolute zero kelvin

Abstract

The thermodynamic properties of Mg48Zn52 were investigated by calorimetry. The standard entropy of formation at 298 K, Δf S 298 o , was determined from measuring the heat capacity, C p , from near absolute zero (2 K) to 300 K by the relaxation method. The standard enthalpy of formation at 298 K, Δf H 298 o , was determined by solution calorimetry in hydrochloric acid solution. The standard Gibbs energy of formation at 298 K, Δf G 298 o , was determined from these data. The obtained results were as follows: Δf H 298 o (Mg48Zn52)=(−1214±(300) kJ · mol−1;ΔfS 298 o (Mg48Zn52)=(−123±0.36) J · K−1 · mol−1; and Δf G 298 o (Mg48Zn52)=(−1177±(300) kJ · mol−1. The electronic contribution to the heat capacity of Mg48Zn52 was found to be approximately equal to pure magnesium, indicating that the density of states in the vicinity of the Fermi level follows the free electron parabolic law.