Use the rate law: rate = k[A]^m[B]^n
Rearrange to solve for the rate constant: k = rate / ([A]^m[B]^n)
Determine the reaction orders m and n from experimental data
Measure the reaction rate experimentally
Measure the reactant concentrations at the same time as the rate
Substitute the values into the rearranged rate law
Calculate k
Use integrated rate laws if concentration changes over time are given
For first-order reactions, use k = ln([A]0/[A]t) / t
For second-order reactions, use k = (1/[A]t – 1/[A]0) / t
For zero-order reactions, use k = ([A]0 – [A]t) / t
Check that units of k match the overall reaction order
Repeat calculations with multiple trials and average the values if needed