ACS Physical Chemistry: Thermochemistry Practice Test

When the Gibbs free energy change (ΔG) is positive, it indicates that the process is non-spontaneous in the forward direction. This means that under standard conditions, the reaction would require an input of energy to proceed, suggesting that it's more favorable to remain with the reactants rather than forming products. The system is in a state of higher energy in the products compared to the reactants, making it unlikely for the reaction to move towards product formation spontaneously.

In thermochemical terms, a positive ΔG reflects that the free energy of the products is greater than that of the reactants, which is not favorable for the reaction to advance toward the right. Therefore, the tendency for the system is to favor the reactants’ formation, supporting the answer that the reaction will proceed to the left, or toward the reactants. This understanding aligns with the principles of thermodynamics, where reactions are driven toward states of lower free energy under equilibrium conditions.