APPLICATION OF THE LE CHATELIER PRINCIPLE ON GAS REACTIONS

Le Chatelier's principle has been the subject of much discussion and c ontroversy because it sometimes seems to give the wrong predictions. A classic example is the ammonia gas reaction. The principle is now re- examined, starting from a strict and general derivation given recently . A chemical reaction in a gas mixture is then considered and the cond itions are derived under which a chemical reaction will increase the a mount of a type of molecule but decrease its chemical potential, a cas e which has caused confusion. It is demonstrated that there are no exc eptions to Le Chatelier's principle if applied to infinitesimal change s of an equilibrium system. However, finite changes may violate the pr inciple. The conditions are given under which this may occur in a gas mixture. The mathematical formulation of the principle is transformed to a form lending itself to quantitative calculations.