Pick your Calculation Mode and enter values like Pre-exponential Factor (A), Activation Energy (Eₐ), and Temperature (T) — or plug in two rate-temperature pairs (k₁/T₁ and k₂/T₂) — and the Arrhenius Calculator works out your Rate Constant, Activation Energy, Rate Ratio (k₂/k₁), and Temperature Effect Factor.
Calculated Result
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Activation Energy
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Rate Ratio (k₂/k₁)
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Temperature Effect Factor
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Activation energy is the minimum energy required for a chemical reaction to occur. It represents an energy barrier that reactant molecules must overcome to form products.
Yes, enzymes act as biological catalysts that lower the activation energy of reactions, making them proceed faster at the same temperature without being consumed in the process.
Plot ln(k) vs 1/T (Arrhenius plot). The slope of this linear relationship equals -Eₐ/R, where R is the gas constant. Multiply the slope by -R to get the activation energy.
While uncommon, negative activation energies are theoretically possible for certain reactions where the reaction rate decreases with increasing temperature, often involving complex mechanisms.
Activation energy is typically expressed in kilojoules per mole (kJ/mol) or joules per mole (J/mol). Sometimes it's also given in electron volts (eV) or calories per mole (cal/mol).
According to the Arrhenius equation, reaction rate increases exponentially with temperature. Even small temperature increases can significantly accelerate reaction rates.
The pre-exponential factor (A) represents the frequency of molecular collisions with proper orientation. It's related to the probability of successful collisions leading to reaction.
The gas constant R (8.314 J/mol·K) converts between energy units and provides the proper scaling factor in the Arrhenius equation to relate temperature and activation energy.