Answer:
-20 kcal/mol (It stays the same)
Explanation:
Enzymes will reduce the Gibbs free energy of activation, but will neither increase or decrease the free energy of reaction.
Enzymes means of activity is by decreasing the activation energy (Ea or ΔG✳) for a reaction. This in turn raises the reaction rate.
Free energy of reaction
= free energy of product - free energy of substrate
The free energy of the product remains constant even without the enzyme. Hence, the enzyme would show no effect on the free energy of the reaction.
The attached image shows the effect of changes in enzyme concentration on the free energy.