Three coupled sets of master equations, representing the equilibration of [Formula: see text] via atoms only, have been solved by the normal-mode technique; the set of 57 simultaneous differential equations describing the H2/D2/2HD system was considered as a suitable trial model. It was found that at times (t) in excess of the longest vibrational relaxation time, even though some of the populations in the system appeared highly non-Boltzmann, all the phenomenological rate constants were well-behaved: they were either constant and obeyed the rate–quotient law, or they were dependent on t2.The paper concludes with a discussion of the information required before a full solution of the [Formula: see text] reaction could be contemplated, and suggests methods by which an approximation to such a solution could be obtained.
