The change in Gibbs Free Energy observed when reactants are converted to products is called which of the following?

• A. Gibbs Free Energy
• B. Gibbs Free Energy Change
• C. Enthalpy Change
• D. Entropy Change

Answer: (B)

The change in Gibbs free energy for a reaction is the Gibbs Free Energy Change, denoted ΔG. This quantity tells you how much energy is available to do useful work when reactants become products at constant temperature and pressure. It combines heat content and disorder through the relation ΔG = ΔH − TΔS, linking enthalpy change and entropy change to temperature.

Interpreting ΔG: if it’s negative, the reaction can proceed spontaneously and releases free energy; if positive, it requires energy input to proceed; if zero, the system is at equilibrium. The other terms describe different things: Gibbs Free Energy itself is a state function, not the change; enthalpy change is about heat content, and entropy change is about disorder. So the observed energy change for the reaction is the Gibbs Free Energy Change.