Spontaneity

Knowing $\Delta H$ is not enough to predict whether a reaction happens on its own. This part builds the real criterion for spontaneity — entropy, and then Gibbs energy, which combines enthalpy and entropy into a single sign test:

• Is Decrease in Enthalpy a Criterion for Spontaneity? — why $\Delta H < 0$ alone isn't enough.
• Entropy and Spontaneity — disorder as the real driving force.
• Gibbs Energy and Spontaneity — combining $\Delta H$ and $\Delta S$ into $\Delta G$.
• Entropy and Second Law of Thermodynamics — the total entropy of system + surroundings. …