First-Order Kinetics (t1/2)Chemistry
First-Order Reaction Kinetics & Half-Life Calculator
Calculate remaining concentration [A]t, concentration-independent half-life (t1/2), and percent consumed over time for first-order chemical and radioactive processes.
Calculated Result
Remaining Concentration [A]t
0M
Calculator Inputs
M
Quick select:
1/time
Quick select:
times
Quick select:
Remaining Concentration [A]t
0M
Reaction Half-Life (t1/2)
13.86 time unit
Percent Consumed (%)
100 %
Regular Exponential Decay: Half-life is constant and concentration-independent, halving remaining substance systematically every interval.
First-Order Exponential Decay Profile
percent_remaining
0(0%)
Consumed %
100 %(100%)
Standard chemical kinetics and pharmacokinetics tool for first-order decay reactions.
Calculation Methodology
First-Order Integrated Rate Law: ln([A]t / [A]0) = -k * t, or [A]t = [A]0 * exp(-k * t). Half-Life: t_1/2 = ln(2) / k ≈ 0.69315 / k. Percent Reacted = (1 - [A]t / [A]0) * 100%.
Frequently Asked Questions
Because the reaction rate is directly proportional to concentration at every moment; doubling the concentration doubles the instantaneous rate, perfectly canceling any effect on the time required for 50% decay.
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