The rate law for the dimerisation of ${\mathrm{NO}}_2$ is:

$-\frac{d\left[{\mathrm{NO}}_2\right]}{dt}=k{\left[{\mathrm{NO}}_2\right]}^2$

which of the following changes will change the value of specific rate constant, $\mathrm{k}$:

Although the concentration of the reactants or products or the total pressure have no effect on the particular reaction rate (or rate constant), temperature does. As a result, the value of the specific reaction rate will vary when the temperature is doubled.