Yield, Selectivity, and All That


  • Ronald W. Missen University of Toronto
  • William R. Smith University of Guelph


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.

Author Biographies

Ronald W. Missen, University of Toronto

Ronald W. Missen is Professor Emeritus (Chemical Engineering) at the University of Toronto. He received his BSc and MSc degrees in chemical engineering from Queen's University and his PhD degree in physical chemistry from the University of Cambridge. He is the coauthor of Chemical Reaction Equilibrium Analysis and Introduction to Chemical Reaction Engineering and Kinetics.

William R. Smith, University of Guelph

William R. Smith is a Professor of Engineering and of Mathematics and Statistics at the University of Guelph. He received his BASc, and MASc degrees in chemical engineering from the University of Toronto, and his MSc and PhD degrees in applied mathematics from the University of Waterloo. He is the coauthor of Chemical Reaction Equilibrium Analysis. His research is in classical and statistical thermodynamics.