Page "Absolute zero" Paragraph 13

thus, as T decreases, ΔG and ΔH approach each other ( so long as ΔS is bounded ).

Experimentally, it is found that all spontaneous processes ( including chemical reactions ) result in a decrease in G as they proceed toward equilibrium.

If ΔS and / or T are small, the condition ΔG < 0 may imply that ΔH < 0, which would indicate an exothermic reaction.

However, this is not required ; endothermic reactions can proceed spontaneously if the TΔS term is large enough.