[Needaask]

During a phase change ΔG=0. So, we can apply the formula ΔG°=-RTlnKeq. However, I don't understand why we are able to use the formula ΔG=ΔH-TΔS. In most cases, the let ΔG=0 so ΔH=TΔS and now they use the ΔH° for the particular phase change and substitute it in the ΔH=TΔS formula.

Wouldn't the ΔH value not be equal to the ΔH° value because the ΔH° depends on the stoichiometric amounts as indicated in the equation? Say 2A B so now for ΔH° it would be the change in enthalpy for 1 mole of B from 2 moles of A. Whereas for ΔH, now that at the equilibrium there is a mixture of both reactants and products. So not all of the 2 moles of A gets converted to 1 mole of B.

Similarly for entropy it is the same thing where i don't think we can just use ΔS° and substitute it for ΔS.

What is wrong with my misconception? Thanks in advance for the help.

[Lete_]

ΔG° = ΔH° - TΔS°   also. I don't know if I understood your question