Svante Arrhenius (1889) empirically found that reaction rate constants follow: k = A · exp(−Ea/RT), where Ea is the activation energy, R = 8.314 J/(mol·K), T is temperature, and A is the pre-exponential (attempt) factor.
The exponential sensitivity to temperature is profound: a 10°C rise near room temperature roughly doubles reaction rates. The energy landscape shows a potential barrier — molecules need enough thermal energy to surmount it. The right panel shows a simulation of molecular collisions: only those with energy above Ea (red) react. The Arrhenius plot (ln k vs 1/T) is linear with slope −Ea/R, allowing Ea to be measured experimentally.