- #1
jdstokes
- 523
- 1
Does anyone know of a clean proof that a reaction will occur at constant temperature if the change in Helmholtz free energy is negative, or at constant temperature and pressure if the change in Gibbs free energy is negative?
The only `proofs' I've found rely on the fact that the entropy change of the system is given by [itex]\Delta Q /T[/itex]. It seems to me as though this assumption is unjustified since the relation [itex]\Delta S = \Delta Q /T[/itex] holds only for reversibly exchanged heat, but chemical reactions are irreversible processes in general.
The only `proofs' I've found rely on the fact that the entropy change of the system is given by [itex]\Delta Q /T[/itex]. It seems to me as though this assumption is unjustified since the relation [itex]\Delta S = \Delta Q /T[/itex] holds only for reversibly exchanged heat, but chemical reactions are irreversible processes in general.