  We extend the energetic variational approach so it can be applied to a
chemical reaction system with general mass action kinetics. Our approach starts
with an energy-dissipation law. We show that the chemical equilibrium is
determined by the choice of the free energy and the dynamics of the chemical
reaction is determined by the choice of the dissipation. This approach enables
us to couple chemical reactions with other effects, such as diffusion and drift
in an electric field. As an illustration, we apply our approach to a
non-equilibrium reaction-diffusion system in a specific but canonical set-up.
We show by numerical simulation that the input-output relation of such a system
depends on the choice of the dissipation.
