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?(adsbygoogle = window.adsbygoogle || []).push({});

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.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Spontaneity of reactions and free energy

**Physics Forums | Science Articles, Homework Help, Discussion**