Arrhenius k
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
About this calculator
The Arrhenius k calculator computes the rate constant (k) of a chemical reaction using the Arrhenius equation. This formula links k to activation energy (Ea), temperature (T), the pre-exponential factor (A), and the gas constant (R). It predicts how reaction rates change with temperature variations.
The formula is k = A * exp(-Ea/(R*T)), where A represents the frequency of effective collisions, Ea is the minimum energy required for the reaction, R is the universal gas constant (typically 8.314 J/(mol·K)), and T is the temperature in Kelvin. The calculator requires A, Ea, R, and T values to produce the result.
It is used in kinetic studies, industrial process optimization, and thermal stability analysis. For instance, it helps compare reaction behavior in ovens versus refrigeration. It can also estimate Ea from experimental data at different temperatures.
Note that the Arrhenius equation assumes A and Ea are constants, which may not hold for complex reactions. Ensure R is in correct units and convert temperature to Kelvin (K = °C + 273.15).
Frequently asked questions
What is the pre-exponential factor (A) in the Arrhenius equation?
Factor A represents the frequency of collisions with the correct orientation between reactant molecules. It is experimentally determined and depends on the nature of the substances involved.
How does temperature affect the value of k?
Increasing temperature reduces the negative exponential (-Ea/R·T), resulting in a higher k. This means reactions proceed faster at elevated temperatures.
What are the units for activation energy (Ea)?
Ea is typically expressed in joules per mole (J/mol) or kilojoules per mole (kJ/mol). Ensure unit consistency when using the calculator.
Can the calculator determine A or Ea from experimental data?
No, the tool calculates k from provided values. To find A or Ea, graphical methods (like plotting ln(k) vs. 1/T) or derived Arrhenius equations are needed.