Activation Energy Calculator
Finds the energy barrier from two rate measurements.
Activation energy Ea
— kJ/mol
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Pre-exponential factor A —
k₂ ÷ k₁ —
Reading this —
The formula
Ea = R × ln(k₂ ÷ k₁) ÷ (1/T₁ − 1/T₂)
T is in kelvin. The ratio of two rate constants cancels A, so it does not need to be known.
What to watch out for
Rates can stand in for rate constants if the concentrations were the same in both runs.
Frequently Asked Questions
What is Ea if a rate doubles from 25 °C to 35 °C?
About 52.9 kJ/mol.
Why must temperatures be in kelvin?
The equation uses 1/T, which only works on an absolute scale.