One of the most common questions in general chemistry and thermodynamics is: *is delta g 0 at equilibrium?Now, * The short answer is yes—when a chemical reaction reaches equilibrium under constant temperature and pressure, the Gibbs free energy change (ΔG) for the system is exactly zero. Even so, this simple statement often causes confusion because students frequently mix up ΔG with ΔG°, the standard Gibbs free energy change. Understanding why ΔG equals zero at equilibrium requires looking at how reactions move toward balance, what the reaction quotient tells us, and the difference between a system at equilibrium and a system under standard conditions.
What Is Gibbs Free Energy (ΔG)?
Gibbs free energy is a thermodynamic potential that measures the maximum amount of non-expansion work a system can perform at constant temperature and pressure. It is defined by the equation:
G = H − TS
where H
