Reaction Inputs
Use consistent units. Leave unrelated fields blank for the selected solve mode.
Formula Used
[A]ₜ = [A]₀ − kt
k = ([A]₀ − [A]ₜ) / t
t = ([A]₀ − [A]ₜ) / k
[A]₀ = [A]ₜ + kt
t½ = [A]₀ / 2k
tcomplete = [A]₀ / k
Zero order kinetics means the reaction rate stays constant and does not depend on concentration. The concentration plot versus time is therefore a straight line with slope −k.
How to Use This Calculator
- Select the variable you want to solve.
- Enter the known values for concentration, rate constant, or time.
- Keep units consistent across all entries.
- Set graph duration manually or leave it blank for automatic scaling.
- Press Calculate to view the result above the form.
- Review the derived values, graph, and physical interpretation.
- Export the result table as CSV or PDF when needed.
Example Data Table
Example case: initial concentration 1.20 mol/L and rate constant 0.05 mol/L/min.
| Time (min) | Initial [A]₀ (mol/L) | Rate constant k (mol/L/min) | Calculated [A]ₜ (mol/L) | Amount reacted (mol/L) |
|---|---|---|---|---|
| 0 | 1.20 | 0.05 | 1.20 | 0.00 |
| 4 | 1.20 | 0.05 | 1.00 | 0.20 |
| 8 | 1.20 | 0.05 | 0.80 | 0.40 |
| 12 | 1.20 | 0.05 | 0.60 | 0.60 |
| 24 | 1.20 | 0.05 | 0.00 | 1.20 |
FAQs
1) What is a zero order reaction?
A zero order reaction proceeds at a constant rate. The rate does not depend on the reactant concentration over the working range.
2) What does this calculator solve?
It can solve concentration at time, initial concentration, elapsed time, rate constant, half life, and depletion time for zero order kinetics.
3) Why is the graph a straight line?
The integrated zero order law is linear in time. That makes the concentration versus time plot a straight descending line with slope equal to negative k.
4) Can the concentration become negative?
No. Negative concentration is not physical. When the entered time exceeds depletion time, the calculator limits the displayed concentration to zero.
5) What units should I use?
Use any consistent concentration and time units. The rate constant automatically follows concentration divided by time, such as mol/L/min.
6) How is half life different here?
For zero order kinetics, half life depends on the initial concentration. It is not constant across all starting concentrations.
7) When is this model appropriate?
Use it when experimental evidence shows a constant rate over time, often under saturation or surface controlled conditions.
8) Does this replace laboratory fitting?
No. It supports quick calculation and interpretation. Experimental data fitting is still important for validating the reaction order and rate constant.