If the rate of reaction, v, is expressible in the form: \[\nu = (k_{0}+\sum _{\begin{array}{c} i \end{array}}k_{i}\ [C_{i}]^{n_{i}})\ [A]^{\alpha }\ [B]^{\beta }\ ...\] where A, B, ... are reactants and Ci represents one of a set of catalysts, then the proportionality factor ki is the catalytic coefficient of the particular catalyst Ci. Normally the partial order of reaction n i with respect to a catalyst is unity, so that ki is an (α + β + ... + 1)th order rate coefficient. The proportionality factor k0 is the (α + β + ...)th order rate coefficient of the uncatalysed component of the total reaction. For example, if there is catalysis by hydrogen and hydroxide ions, and the order of reaction can be expressed in the form: \[k = k_{0}+k_{\text{H}^{+}}\ [\text{H}^{+}]+k_{\text{OH}^{-}}\ [\text{OH}^{-}]\] then kH+ and kOH- are the catalytic coefficients for H⁺ and OH⁻, respectively. The constant k0 relates to the uncatalysed reaction.