basic

Half-Life of a Second-Order Reaction Calculator

t½ = 1 / (k · [A]₀) — depends on initial concentration.

Compute the half-life of a second-order reaction A → products from the rate constant k (M⁻¹·s⁻¹) and the initial concentration [A]₀: t½ = 1 / (k · [A]₀). Unlike first-order kinetics, the half-life of a second-order reaction lengthens as the reactant is consumed (because [A]₀ decreases).

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

M⁻¹·s⁻¹
M

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

t½ = 1 / (k · [A]₀).

In depth

Compute the half-life of a second-order reaction A → products from the rate constant k (M⁻¹·s⁻¹) and the initial concentration [A]₀: t½ = 1 / (k · [A]₀). Unlike first-order kinetics, the half-life of a second-order reaction lengthens as the reactant is consumed (because [A]₀ decreases).