In a previous paper [5], it was shown how an arbitrary system of flow-mixing and splitting with plug sections in between could be modelled by a discrete residence time distribution (macro-mixing) and micro-mixing only between streams having equal remaining life. It is demonstrated in this paper how one may generalize these concepts to include the continuous descriptions of both of these mixing functions. These results are embodied in a mathematical model (General Mixing Model) which contains the macro-mixing and micro-mixing appearing as explicit functions and this model is valid for steady flow reactors in which systems of reactions with arbitrary kinetics (linear and non-linear) take place. This statement is true as long as there is no volume change on mixing or reaction, and we have a single unique residence time distribution for all the species in the system.