Electrical work, from chemical transformations

The free energy functions are defined by explicit equations in which the variables are functions of the state of the system. The change of a state function depends only on the initial and final states. It follows that the change of the Gibbs free energy (AG) at fixed temperature and pressure gives the limiting value of the electrical work that could be obtained from chemical transformations. AG is the same for either the reversible or the explosively spontaneous path (e.g. H2 -I- CI2 reaction) however, the amount of (electrical) work is different. Under reversible conditions... 

Systems for extracting, transforming, and using energy from the environment (Fig. 1-lb), enabling organisms to build and maintain their intricate structures and to do mechanical, chemical, osmotic, and electrical work. Inanimate matter tends, rather, to decay toward a more disordered state, to come to equilibrium with its surroundings. 

An elementary act of a traditional homogeneous redox reaction can be considered as a collision of the reacting particles with a simultaneous electron transfer from the reductant to the oxidant. This approach does not work with electrochemical processes. Here, the reactant and the oxidant are separated in space and the electron transfer occurs through the external circuit. Thus, an electrochemical reaction is accompanied by electron flow. The directed electron flow might be induced by a spontaneous reaction in the circuit. In this case, one deals with a Galvanic cell. On the craitrary, in an electrolytic cell, the electric current from an external source may cause non-spontaneous chemical transformations. 

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