According to this formula, when:
ΔG = ΔH - T*ΔS
when the reaction is thermodynamically spontaneous ΔG < 0
∴ ΔH - T* ΔS = 0
∴T*ΔS = ΔH
∴ T = ΔH / ΔS
when we have:
ΔH = -70KJ
and ΔS = -0.4 KJ/K
So by substitution:
T = -70KJ /- 0.4
= 175 K
∴the certain temperature below which the reaction will be thermodynamically spontaneous is 175 K
