The Exponential Barrier
The Arrhenius equation reveals why temperature is the master variable of chemical kinetics. The exponential factor exp(−Ea/RT) represents the fraction of molecular collisions with sufficient energy to overcome the activation barrier. Even a modest activation energy of 75 kJ/mol means that at room temperature, only about 1 in 10¹³ collisions succeeds — yet reactions still proceed because molecules collide trillions of times per second.
The Arrhenius Plot
Taking the natural logarithm of k = A × exp(−Ea/RT) gives ln(k) = ln(A) − Ea/(RT), a straight line when plotted against 1/T. The slope gives −Ea/R and the intercept gives ln(A). This linearization, proposed by Arrhenius in 1889, remains the standard method for extracting activation energies from experimental rate data. Deviations from linearity reveal non-Arrhenius behavior such as quantum tunneling or complex mechanisms.
Temperature Sensitivity
The common rule of thumb that reaction rates double per 10°C increase is only approximately correct, and only near room temperature for moderate activation energies. This simulation lets you explore the actual rate ratio for any Ea and T combination. High activation energies produce extreme temperature sensitivity — enzyme-catalyzed reactions with low Ea are deliberately temperature-insensitive, while explosives have high Ea for safety.
Energy Diagram
The visualization shows a potential energy surface with reactants, transition state, and products. The activation energy appears as the height of the barrier, and the Boltzmann distribution of molecular energies is overlaid to show what fraction exceeds Ea. As you increase temperature, the distribution broadens and more molecules clear the barrier — the visual origin of the Arrhenius exponential.