ENGINEERING – CHEMICAL ENGINEERING CALCULATOR
Arrhenius Rate Constant
A precise tool.
What is the Arrhenius Rate Constant & How does it work?
The Arrhenius equation provides a quantitative relationship between temperature and the rate constant of a chemical reaction, reflecting how molecular collisions become more energetic as temperature rises. The activation energy, Eₐ, represents the minimum energy barrier that reacting species must overcome; a higher Eₐ dramatically slows the reaction at a given temperature. By inserting experimentally determined values for A, Eₐ, and T into the equation, engineers can predict reaction rates, design reactors, and assess how temperature changes will impact process performance.
k = A \exp\left(-\frac{E_a}{R T}\right)
k = rate constant (s⁻¹)
A = pre‑exponential factor (s⁻¹)
E_a = activation energy (J·mol⁻¹)
R = universal gas constant (8.314 J·mol⁻¹·K⁻¹)
T = absolute temperature (K)
A = pre‑exponential factor (s⁻¹)
E_a = activation energy (J·mol⁻¹)
R = universal gas constant (8.314 J·mol⁻¹·K⁻¹)
T = absolute temperature (K)
Parameters
Result
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Frequently Asked Questions
What is the Arrhenius equation used for?
The Arrhenius equation is used to determine how temperature affects the rate constant of a chemical reaction.
How do I calculate the activation energy using the Arrhenius equation?
Rearrange the Arrhenius equation to solve for E_a: E_a = -R * ln(k2/k1) * (T2 - T1) / (T2 * T1), where k1 and k2 are rate constants at temperatures T1 and T2.
What is the significance of the pre-exponential factor A in the Arrhenius equation?
The pre-exponential factor A represents the frequency of collisions between reactant molecules that have enough energy to overcome the activation barrier.
How does temperature affect the rate constant k according to the Arrhenius equation?
As temperature increases, the rate constant k increases exponentially due to more frequent and energetic molecular collisions.
What is the universal gas constant R in the Arrhenius equation?
The universal gas constant R is 8.314 J·mol⁻¹·K⁻¹, used to convert temperature from Kelvin to energy in joules per mole.
Can I use Celsius instead of Kelvin in the Arrhenius equation?
No, you must use absolute temperature (Kelvin) in the Arrhenius equation because it affects the exponential term directly.
How do I interpret the rate constant k obtained from the Arrhenius equation?
The rate constant k indicates how quickly a reaction will proceed at a given temperature; higher k values mean faster reaction rates.
Results are for informational purposes only and do not constitute professional advice.