Although thermodynamic calculations, which are derived by various computational methods
based on the available reference data, and experimental methods yield considerable uncertainties [22,24],
the calculated thermodynamic values for PGM appear to be in a good agreement with those given inthe literature. In addition, to evaluate the accuracy of the method of the calculation of the Gibbs free
energy of formation, the (DfG) for the rhodium sulfide phases Rh3S4 and Rh2S3were calculated using
the HSC program (Tables 2 and 3). The Reaction Equations mode was used to estimate the free energy
of Reactions (6) and (7) through Equation (3), combining data from the HSC main database