First-Order Half-Life Calculator
First-order half-life calculator
Calculate first-order kinetic half-life from rate constant.
Result
t1/2 = 30.1368339374
Uses first-order relation t1/2 = ln(2)/k.
Chem signal
Advanced options
Flow
- Enter first-order rate constant k in 1/time.
- Compute half-life directly using ln(2)/k.
- Interpret output in the same time unit basis as k.
Example
Worked example: k = 0.023 s^-1
- 1 Apply t1/2 = ln(2)/k.
- 2 Compute 0.693147/0.023.
- 3 Result is about 30.14 seconds.
Half-life is approximately 30.14 time units.
How
- Enter first-order rate constant k in 1/time.
- Compute half-life directly using ln(2)/k.
- Interpret output in the same time unit basis as k.
Avoid
- Applying first-order half-life formula to non-first-order reactions.
- Using k with inconsistent time units.
Checks
Best fit
First-Order Half-Life Calculator is built for calculate first-order reaction half-life from rate constant. If First-Order Half-Life Calculator does not match the input scope, compare the answer with a second method.
Input check
Match the entered values to this rule before copying the answer: t1/2 = ln(2) / k.
Sanity check
For First-Order Half-Life Calculator, use the worked example as a quick benchmark: Half-life is approximately 30.14 time units. If the first-order half-life calculator answer is far away, check whether an input, unit, or mode changed.
Before copying
Review this common issue first: applying first-order half-life formula to non-first-order reactions.
Ref only. Verify values. Follow lab safety.
FAQ
Does half-life depend on concentration for first order?
No. First-order half-life is concentration-independent.
Can I use min^-1 rate constants?
Yes. Output half-life will be in minutes if k is per minute.
What if k is zero?
k must be greater than zero for finite decay half-life.
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