When analyzing kinetic data or designing a chemical reactor, it is important to state clearly the definitions of reaction rate, conversion, yield, and selectivity. For a homogeneous reaction, the reaction rate is defined either as the amount of product formed or the amount of reactant consumed per unit volume of the gas or liquid phase per unit time. We generally use moles (g mol, kg mol, or lb mol) rather than mass to define the rate, since this simplifies the material balance calculations.
