The activation energy for a reaction can be determined by measuring the reaction rate at different:

The activation energy for a reaction is determined by measuring the reaction rate at different temperatures.

The Arrhenius equation helps us to determine this.

$2.303\log \frac{K_2}{K_1}=\frac{E_2}{R}\left[\frac{T_2-T_1}{{\mathrm{T}}_1{\mathrm{T}}_2}\right]$