Backward Reaction Rate Constant given kf and Keq is usually measured using the Liter per Mole Second[L/(mol*s)] for Second Order Reaction Rate Constant. Cubic Meter per Mole Second[L/(mol*s)], Cubic Meter per Kilomole Millisecond[L/(mol*s)], Liter per Mole Millisecond[L/(mol*s)] are the few other units in which Backward Reaction Rate Constant given kf and Keq can be measured.