Question

For the reaction
2A_(g) + B_(g) ➝ 2D_(g)
∆U° = -10.5 kJ and ∆S°= -44.1 JK^-1.
Calculate ∆G° for the reaction and predict whether the reaction may occur spontaneously.

Answer 1

For the given reaction,

When we substitute the values of ∆H^θ and ∆S^θ in the expression of ∆G^θ, then according to Gibbs’ Helmholtz equation;
∆G^θ = ∆H^θ – T∆S^θ
= -12.98 kJ – (298 K) (-44.1 J K^-1)
=-12.98 kJ - (-13.14 kJ)
∆G^θ = 0.16 kJ
Since ∆G^θ for the reaction is positive, the reaction will not occur spontaneously.