The Rate Constant for Zero Order Rxn using k1 is equal to the rate of the reaction because in this case the rate of reaction is proportional to zero power of the conc of the reactant. And is denoted by k0,k1. Rate Constant for Zero Order Rxn using k1 is usually measured using the Mole per Cubic Meter Second for Reaction Rate. Note that the value of Rate Constant for Zero Order Rxn using k1 is always positive.