How to Calculate Activation Energy
What is Activation Energy?
Activation energy (Ea) is the minimum energy required for a chemical reaction to occur — the energy barrier reactants must overcome to form products. It can be calculated from reaction rate constants at two temperatures using the Arrhenius equation.
Step-by-Step Guide
- 1ln(k2/k1) = Ea/R × (1/T1 − 1/T2)
- 2R = 8.314 J/mol·K
- 3k1, k2 = rate constants at T1, T2 (in Kelvin)
- 4Ea = R × ln(k2/k1) / (1/T1 − 1/T2)
Worked Examples
Input
k doubles from 300K to 310K
Result
Ea ≈ 53.6 kJ/mol
ln(2)/8.314 × (1/300−1/310)⁻¹ = 53.6 kJ
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