Arrhenius Equation Calculator
Calculate rate constants, activation energy, or required temperature using the Arrhenius equation: k = Ae^(-Ea/RT). Supports single-point calculations (given A and Ea) and two-point calculations (given k at two temperatures).
The Arrhenius equation describes how the rate constant of a chemical reaction depends on temperature. It is one of the most important equations in chemical kinetics.
The Equation: k = Ae^(-Ea/RT)
- k = rate constant (units depend on reaction order)
- A = pre-exponential factor (frequency factor, same units as k)
- Ea = activation energy (J/mol or kJ/mol)
- R = gas constant = 8.314 J/(mol·K)
- T = absolute temperature (K)
Two-Point Form (Arrhenius Plot):
When you have rate constants at two temperatures, you can find activation energy without knowing A: ln(k₂/k₁) = (Ea/R)(1/T₁ - 1/T₂). This is derived from taking the ratio of the Arrhenius equation at two temperatures.
Physical Meaning:
The activation energy Ea represents the minimum energy barrier that must be overcome for a reaction to occur. Higher Ea means the reaction is more sensitive to temperature changes. The pre-exponential factor A represents the frequency of molecular collisions with the correct orientation. A plot of ln(k) vs 1/T gives a straight line with slope = -Ea/R.