A term sometimes used for a @R05137@. For example, if the rate equation is: \[v=k\ \text{[A]}\ \text{[B]}\] the function \(k\ \text{[A]}\) is the pseudo first-order @O04322@ (or first-order @R05137@) with respect to B. Similarly, \(k\ \text{[B]}\) is the pseudo first-order @O04322@ (or first-order @R05137@) with respect to A. The term pseudo @O04322@ is particularly useful when the concentration of one reactant is much greater than that of another.