What is the Arrhenius Equation?

The Arrhenius equation is a critical formula in chemical kinetics that describes how the rate of a chemical reaction depends on the temperature. Developed by Svante Arrhenius in 1889, it links the rate constant (k) to the absolute temperature (T) and the activation energy (Ea) of the reaction. In simple terms, it explains why most chemical reactions speed up as temperature increases.

The Formula

The standard form of the equation is: k = A · e^(-Ea / RT)

• k: Rate Constant (speed of the reaction).
• A: Pre-exponential factor (frequency of collisions).
• Ea: Activation Energy (Joules per mole).
• R: Universal Gas Constant (8.314 J/mol·K).
• T: Absolute Temperature in Kelvin (K).

How to Use This Calculator

This tool allows you to solve for any of the variables in the Arrhenius equation. Simply select the variable you want to find, input the known values (ensuring temperature is in Kelvin and energy is in Joules), and click calculate. The tool will provide the result and a step-by-step mathematical breakdown of how the result was derived.

Frequently Asked Questions

Why is Kelvin used instead of Celsius?

Thermodynamic equations require absolute temperature. Since zero Kelvin represents absolute zero (where molecular motion stops), it provides the necessary scale for the exponential relationship in kinetics.

What does Activation Energy mean?

Activation energy (Ea) is the minimum amount of energy that reacting species must possess to undergo a specified reaction. Higher Ea values result in slower reaction rates because fewer molecules have enough energy to overcome the barrier.