What is Thermodynamic Principle of Metallurgy

In using thermodynamic principle of metallurgy, we apply the concepts of thermodynamics such as Gibb's energy (ΔG) and entropy (S) to the principles of extraction of different metals. The change in Gibbs energy, ΔG for any process at any specified temperature T, is described by the following equation :

ΔG = ΔH – TΔS

where, ΔG is Gibbs energy, ΔH is the enthalpy change and ΔS is the entropy change for the process. But the reaction will occur only when ΔG for the reaction is negative.

If the reactants and the products of the two reactions are put together in a system and the net ΔG of the two reactions is negative, then only the overall reaction will occur.

Thus the process of interpretation involves coupling of the two reactions, getting the sum of their ΔG and looking for its magnitude and sign. In this way, the thermodynamic concepts help us in understanding the theory of metallurgical transformations.