Rate Constant Calculator Formula

Understand the math behind the rate constant calculator. Each variable explained with a worked example.

Use the Rate Constant Calculator

Formulas Used

Rate Constant (k)

k = a_factor * pow(e, -ea / (8.314 * temp))

Variables

VariableDescriptionDefault
a_factorPre-exponential Factor (A)10000000000
eaActivation Energy (Ea)(J/mol)50000
tempTemperature (T)(K)298

How It Works

Arrhenius Equation

Formula

k = A × e^(−Ea / RT)

Where:

  • k = rate constant
  • A = pre-exponential (frequency) factor
  • Ea = activation energy (J/mol)
  • R = 8.314 J/(mol·K)
  • T = temperature (K)

    • The rate constant increases exponentially with temperature and decreases with higher activation energy.

    Worked Example

    A = 1 × 10¹⁰, Ea = 50,000 J/mol, T = 298 K.

    a_factor = 10000000000ea = 50000temp = 298
    1. 01k = A × e^(-Ea/RT)
    2. 02k = 1×10¹⁰ × e^(-50000/(8.314×298))
    3. 03k = 1×10¹⁰ × e^(-20.18)
    4. 04k = 1×10¹⁰ × 1.71×10⁻⁹
    5. 05k = 17.1

    Ready to run the numbers?

    Open Rate Constant Calculator