Which reaction has a positive $\Delta$G°, assuming that entropy changes are negligible compared to enthalpy changes?

Question

Quizplus · Accepted Answer

The reaction with a positive standard free energy change (∆G°) (F1F1F1S1 -> F1F1F1S2) must have a positive standard enthalpy change (∆H°) as well, since ∆G° = ∆H° - T∆S°. Therefore, we need to look for a reaction where the products have stronger bonds than the reactants. In reaction A (2NH3 -> N2 + 3H2), a total of 4 N-H bonds and 2 N≡N bonds are broken, but a total of 6 H-H bonds are formed in the products. Since H-H bonds are stronger than N-H and N≡N bonds, the products have overall stronger bonds than the reactants, and the reaction has a positive ∆H°. Therefore, the answer is A.

Which Reaction Has a Positive Δ\DeltaΔ G°, Assuming That Entropy Changes Are Negligible Compared to Enthalpy

Which Reaction Has a Positive $\Delta$ G°, Assuming That Entropy Changes Are Negligible Compared to Enthalpy