For a specified set of feed streams and a specified network of chemical reactions, there is an almost limitless variety of reactor-separator designs that might be employed in enhancing the production rates of certain desired molecules while suppressing the production rates of undesired ones. Of special significance is the vast spectrum of very different reactor configurations available to the designer. Here we seek to determine sharp kinetic bounds on what can be achieved in steady-state reactor-separator systems of arbitrary design, subject perhaps to certain natural physical constraints. A primary conceptual tool is the continuous flow stirred tank reactor (CFSTR) equivalence principle, proven here, which asserts that the effluent of any steady-state reactor-separator design can be achieved arbitrarily closely by another steady-state design involving perhaps arbitrarily sharp separations but in which the only reactor components are s + 1 ideal CFSTRs, where s is the rank of the underlying network of chemical reactions. Thus, for the sole purpose of assessing bounds a surprisingly narrow and simple class on the set of attainable effluents, it suffices to consider of reactor configurations.