A mechanism enabling complex chain reactions to give simple rate laws in chemical kinetics. An example of a Rice–Herzfeld mechanism occurs with the pyrolysis of acetaldehyde, the mechanism consisting of initiation, propagation (in two steps), and termination. This leads to the experimental result that the overall reaction is three-halves order in CH₃CHO. To ascertain that such a mechanism is correct, either the steady-state approximation is used or the differential equations for the reaction rates are solved numerically. It is possible, as in this example, for the Rice–Herzfeld mechanism to give a correct description of the main part of the reaction but not to take account of reactions that produce by-products. The Rice–Herzfeld mechanism is named after Francis Rice and Karl Herzfeld, who put forward the scheme in 1934.