Arrhenius Equation Calculator
Rate constant at two temperatures, how much faster the reaction gets, and the ten-degree factor.
Results
What this tool does
The activation energy is the hill the molecules have to climb before anything happens, and temperature decides how many of them have enough energy to get over it. Because the relationship is exponential, a modest warming can change the rate dramatically — which is why food keeps in a fridge and why cold engines wear faster.
Formula
k = A × e^(−Ea ÷ RT)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
ea | Activation energy | kJ/mol |
t1 | Temperature | °C |
t2 | Temperature | °C |
af | Pre-exponential factor | 1/s |
K1 | Rate constant | 1/s |
K2 | Rate constant | 1/s |
RA | Ratio | — |
Q10 | Ratio | — |
Worked example
- Activation energy50 kJ/mol
- Temperature25 °C
- Temperature35 °C
- Pre-exponential factor1,000,000,000,000 1/s
- Rate constant1739.31796809 1/s
- Rate constant3346.90836957 1/s
- Ratio1.92426
- Ratio1.92426
Limitations
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
Frequently asked questions
Is the rule that reactions double every ten degrees true?
It is a rough rule that happens to hold for a common range of activation energies near room temperature, and the last result shows it for your own numbers. An activation energy around 50 kJ/mol does roughly double over ten degrees; a low barrier barely changes, and a high one can triple. The rule is a useful habit of thought, not a law.