Arrhenius Equation Calculator (Rate Constant and Activation Energy)
Find how a reaction rate changes with temperature, or the activation energy from two measurements.
Your numbers
Your results
Arrhenius Equation Calculator (Rate Constant and Activation Energy) by TheCalcTools
How the Arrhenius Equation Calculator (Rate Constant and Activation Energy) works
The Arrhenius equation k = A e^(−Ea/RT) links a rate constant to temperature. Comparing two temperatures removes the unknown factor A.
A common rule of thumb is that reaction rates roughly double for every 10 °C rise near room temperature, which corresponds to an activation energy of about 50 kJ/mol.
The formula
Worked example
Using the default values shown in the calculator:
| Solve for | Rate constant k₂ at a new temperature |
|---|---|
| Rate constant k₁ | 0.0025 |
| Temperature T₁ (°C) | 25 |
| Temperature T₂ (°C) | 35 |
| Activation energy Ea (kJ/mol) | 50 |
| Rate constant k₂ | 0.0048 |
- With Ea = 50 kJ/mol, going from 25 °C to 35 °C multiplies k by 1.924.
- k₂ = k₂ = 0.0048107.
Result:
| Answer | k₂ = 0.0048107 |
|---|---|
| Rate ratio k₂ ÷ k₁ | 1.924 |
| Pre-exponential factor A | 1437000 |
Frequently asked questions
Does a catalyst change the activation energy?
Yes, a catalyst provides a pathway with a lower activation energy, so the rate increases at the same temperature.
Sources and further reading
Related calculators
More in Chemistry · All calculators
This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.