if the macroscopic (observed, empirical or phenomenological) rate of reaction (v) for any reaction can be expressed by an empirical differential rate equation (or rate law) which contains a factor of the form k [A]α [B]β ... (expressing in full the dependence of the rate of reaction on the concentrations [A], [B] ...) where α, β are constant exponents (independent of concentration and time) and k is independent of [A] and [B] etc. (rate constant, rate coefficient), then the reaction is said to be of order α with respect to A, of order β with respect to B, ... , and of (total or overall) order n = α + β + ..., reaktsiooni järk on suurus, mis arvuliselt võrdub reageerivate ainete kontsentratsioonide astmenäitajate summaga reaktsioonikiiruse võrrandis