Calculadora de Equação de Arrhenius
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
k = A·exp(−Ea/RT) ; R = 8,314 J/(mol·K)
About this calculator
The Arrhenius Equation Calculator solves for the reaction rate k using the formula k = A·exp(−Ea/RT). It is essential for chemists and engineers who need to predict how temperature affects the speed of chemical reactions. Simply enter the pre-exponential factor A, the activation energy Ea in J/mol, and the temperature T in Kelvin. The gas constant R is fixed at 8.314 J/(mol·K). The result is the value of k, indicating how fast the reaction proceeds.
This tool is useful in chemical kinetics, reactor design, and stability studies. For instance, by adjusting the temperature of an industrial process, you can estimate the new k and optimize production. It also helps compare catalysts: a catalyst lowers Ea, increasing k. The calculator handles positive values of A and Ea, and T must be greater than zero.
Cautions: ensure units are consistent. Ea must be in J/mol (not kJ/mol). If you enter Ea in kJ/mol, multiply by 1000. Temperature must be absolute in Kelvin (K = °C + 273.15). The calculator assumes the reaction follows the Arrhenius law, valid for many reactions, but not all (e.g., complex reactions or non-elementary mechanisms).
Frequently asked questions
What does a very high k value mean?
A high k indicates a fast reaction. This can be due to high temperature, low activation energy, or a large pre-exponential factor.
Can I use the calculator for gas-phase and liquid-phase reactions?
Yes, the Arrhenius equation is widely applicable, but check if the reaction is elementary. For complex reactions, k may not follow the law perfectly.
What if I have activation energy in kJ/mol?
Convert to J/mol by multiplying by 1000. For example, 50 kJ/mol becomes 50000 J/mol. The calculator expects J/mol.
Why must temperature be in Kelvin?
The equation uses the gas constant R in J/(mol·K), so temperature must be in the same unit (Kelvin). Celsius won't work because it adds an offset.
Does the calculator work for catalyzed reactions?
Yes, the catalyst changes the activation energy (Ea) and/or the A factor. Enter the new values to get the catalyzed k.