Rate Constant for First Order Reaction in MFR is usually measured using the 1 Per Second[s⁻¹] for First Order Reaction Rate Constant. 1 Per Millisecond[s⁻¹], 1 Per Day[s⁻¹], 1 Per Hour[s⁻¹] are the few other units in which Rate Constant for First Order Reaction in MFR can be measured.