Chemistry

First-Order Half-Life

Half-life of a first-order reaction.

Formula

Formula
t½ = ln 2k

Variables

SymbolDefinitionType & rangeUnitsRole
k rate constant (1/s) real number (ℝ) input

Try it yourself

Interactive calculator
Result

Worked examples

Example 1
Givenrate constant k = 0.005
Result138.6294361
Example 2
Givenrate constant k = 0.1
Result6.931471806