chapter  25
39 Pages

ThermodynamicsEntropy and Free Energy

WithPatrick E. McMahon, Rosemary F. McMahon, Bohdan B. Khomtchouk

The entropy of a system is a measure of the disorder, or randomness, of that system. The larger the entropy value the greater the randomness, or disorder, of the system; the smaller the entropy value, the lesser the randomness or disorder. A chemical process is a chemical reaction or physical change. The change in entropy for any process relates to the degree of disorder of the reactants compared to the products. The change in the entropy of a system is a positive value whenever entropy increases; the system becomes more disordered and tends toward a more probable arrangement of matter. A conventional chemical reaction describes the process of converting a specific set of reactants to a specific set of products. The corresponding balanced equation, read from left-to-right, describes the forward reaction. Potential energy change is one main criterion for determining the spontaneous direction of a chemical process.