Reaction Rate Constant for Initiation Step is defined as the rate constant for the first reaction step in which highly reactive intermediates species like free radicals, atoms are formed. And is denoted by k1. Reaction Rate Constant for Initiation Step is usually measured using the Liter per Mole Second for Second Order Reaction Rate Constant. Note that the value of Reaction Rate Constant for Initiation Step is always negative. Typically, the value of Reaction Rate Constant for Initiation Step is greater than 0.