The General Equations of Change for Nonequilibrium Systems

In an isolated system 1 with n components and r chemical reaction mechanisms, the system passes through a sequence of nonequilibrium states, and entropy is produced until the system reaches chemical equihbrium at which point the rate of change of each reaction coordinate is zero. The evaluation of entropy production as a function of time from a state that is not stable to a stable equilibrium state may not be possible. This evaluation requires the solution of a general equation of motion. However, we can approximate the rate of entropy production in terms of the r affinities of system 2, a surrogate for 1, and the rates of change of the reaction coordinates of the r chemical reactions. The surrogate system 2 is a simple system consisting of the same r reactions as system 1, but will have all the chemical reaction mechanisms inhibited. At time t, the amounts of n species satisfy ... 

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