Find activation energy from two rate constants at two temperatures with the two-point Arrhenius equation.
Result
How to use this tool
Enter k1 and k2 measured for the same reaction.
Enter T1 and T2 in kelvin or Celsius.
Read Ea in kJ/mol and J/mol.
Check the rate ratio and the reciprocal-temperature difference for sense.
Formula & worked example
A rate that doubles from 300 K to 310 K implies an activation energy of about 53.6 kJ/mol.
Limitations — read this before you rely on it
Two-point estimate only: it assumes a single mechanism and constant Ea between the two temperatures, and it is sensitive to measurement error in k.
Frequently asked questions
One rate constant fixes only a combination of A and Ea; two points let Ea be separated from the pre-exponential factor.
Yes, the tool converts to kelvin; the equation itself requires absolute temperature.
That implies a negative apparent activation energy, which usually signals a changed mechanism or bad data, so the tool flags it.
Only approximately; over wide ranges the apparent Ea can drift, so keep the interval modest.
Any consistent rate-constant units, since only the ratio k2/k1 enters the formula.