At temperatures greater than 756 °C this reaction is spontaneous under standard conditions.
Explanation:
Let's consider the following reaction.
C(s) + H₂O(g) ⇄ CO(g) + H₂(g)
The reaction is spontaneous when the standard Gibbs free energy ΔG° < 0. ΔG° is related to the standard enthalpy of the reaction (ΔH°) and the standard entropy of the reaction (ΔS°) through the following expression.
ΔG° = ΔH° - T.ΔS°
If ΔG° < 0
ΔH° - T.ΔS° < 0
ΔH° < T.ΔS°
T > ΔH°/ΔS° = (131.3 × 10³ J/mol)/(127.6 J/K.mol) = 1029 K
