Entropy:A measure of the disorder or randomness in a system. Spontaneous reactions often lead to an increase in entropy.
Gibbs Free Energy:This is a thermodynamic potential that measures the maximum reversible work that a system can perform at constant temperature and pressure. If Gibbs free energy is negative, the reaction will be spontaneous.
Exothermic Reaction:A type of chemical reaction where heat is released. Many spontaneous reactions are exothermic.