How to use the first order time to reach a fraction calculator
Find how long a first-order reaction takes to leave a given fraction of reactant. Enter rate constant, fraction remaining in the fields above; the time to reach fraction, time in minutes are computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “first order time to fraction remaining”, “how long until 25 percent left”, “ln equation time”, “calculate first order time to reach a fraction”, “find time to reach fraction”.
Formula
Variables
- k — Rate constant (s⁻¹)
- f — Fraction remaining (%)
Worked example
With rate constant = 0.02 s⁻¹, fraction remaining = 25 %, the calculator gives time to reach fraction ≈ 69.31472 s; time in minutes ≈ 1.155245 min.
Frequently asked questions
What is the first order time to reach a fraction calculator used for?
Find how long a first-order reaction takes to leave a given fraction of reactant. It helps with questions such as “first order time to fraction remaining”, “how long until 25 percent left”, “ln equation time”.
What is the formula for the first order time to reach a fraction calculation?
Time to reach fraction (s) = ln(100 / f) / k. Time in minutes (min) = [Time to reach fraction] / 60. Here k is rate constant (s⁻¹), f is fraction remaining (%).
What inputs do I need for the first order time to reach a fraction calculator?
You need rate constant in s⁻¹, fraction remaining in %. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the first order time to reach a fraction calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the first order time to reach a fraction result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.