A generalized formula to predict the direction of an equilibrium shift, partial derivative(2)f/partial derivative xi(2) partial derivative xi/partial derivative t partial derivative/partial derivative xi(partial derivative f/partial derivative t) < 0, is presented, where xi is the extent of the reaction, t is the characteristic variable to affect an equilibrium and f is the characteristic function whose partial differential with respect to can be used as an equilibrium criterion. When the stable equilibrium of a thermodynamic system is disturbed on condition that f exhibits a minimum with respect to xi, the equilibrium will shift in the direction to resist the increase of f if the disturbance make f increase; however, the equilibrium will shift in the direction to accelerate the decrease of f if the disturbance make f decrease to minimize f. On condition that f exhibits a maximum with respect to xi the equilibrium will shift in the direction to resist the decrease of f if the disturbance make f decrease; however, the equilibrium will shift in the direction to accelerate the increase of f if the disturbance make f increase to maximize f. On the other hand, Le Chatalier's Principle is not consistent with the real situations under certain circumstances.
展开▼
