The maximum work output in a chemical reaction at

The (maximum) reversible work in steady flow between reactants at an entry state Rq(Po, Tq) and products at a leaving state Pq(po, Tq) is 

It is supposed here that the various reactants entering are separated at ( o. o) the various products discharged are similarly separated at (po.To). The maximum work may then be written as 

Kotas [3] has drawn a distinction between the environmental state, called the dead state by Haywood [1], in which reactants and products (each at po. To) are in restricted thermal and mechanical equilibrium with the environment and the truly or completely dead state , in which they are also in chemical equilibrium, with partial pressures (/)j) the same as those of the atmosphere. Kotas defines the chemical exergy as the sum of the maximum work obtained from the reaction with components atpo. To, [—AGo], and work extraction and delivery terms. The delivery work term is Yk k kJo ln(fo/pt), where Pii is a partial pressure, and is positive. The extraction work is also Yk kRkTo n(po/Pk) but is negative. 

In general, we shall not subsequently consider these extraction and delivery work terms here, but use [ —AGq] as an approximation to the maximum work output obtainable from a chemical reaction, since the work extraction and delivery quantities are usually small. Their relative importance is discussed in detail by Horlock et al. [4]. 

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