Calculate First Order Reaction Half-Life
Expert Guide to Calculating First Order Reaction Half-Life
First order reactions are crucial in chemistry, and understanding their half-life is vital. This guide explains how to calculate it and provides a user-friendly calculator.
- Enter the rate constant (k) in the provided field.
- Enter the time (t90) in hours in the second field.
- Click the “Calculate” button.
The half-life (t1/2) of a first order reaction is calculated using the formula:
t1/2 = ln(2) / k
Examples
- Radioactive Decay: Half-life of Carbon-14 is 5700 years. If k = 0.000121, what’s t90?
- Drug Metabolism: Half-life of a drug is 3 hours. If k = 0.231, what’s t90?
Comparison of Half-Life Calculations
| Substance | Rate Constant (k) | Time (t90) | Half-Life (t1/2) |
|---|---|---|---|
| Carbon-14 | 0.000121 | 5700 years | 5700 years |
| Drug X | 0.231 | 3 hours | 3 hours |
Tips
- Always use consistent units for time.
- Understand the limitations of the first order reaction model.
What if my reaction is not first order?
This calculator is for first order reactions only. For other reaction orders, use different formulas.
Can I use this calculator for half-life of other processes?
Yes, the principles apply to any first order process, like radioactive decay or drug metabolism.
For more information, see: