Yield, Selectivity, and All That

Ronald W. Missen, William R. Smith

For a reacting system, simple or complex, operational definitions are given for yield and selectivity of products, as well as fractional conversion of reactants, for both a stoichiometric approach (using stoichiometric coefficients from chemical equations) and a nonstoichiometric approach (using element-conservation equations without chemical equations).  This is in light of considerable variety and possible confusion in the literature about measures of reaction "efficiency."  Examples are provided to illustrate both approaches.