A Generalized Formula to Predict the Direction of an Equilibrium Shift

A generalized formula to predict the direction of an equilibrium shift, , is presented, where ξ 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 ξ 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 ξ, 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 ξ, 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