How to use (3 steps)
- Enter up to four species with their roles (reactant/product), stoichiometric coefficients, and initial concentrations or partial pressures.
- Select Kc or Kp, enter the equilibrium constant, and optionally toggle the small-x approximation check.
- Compute to generate the ICE table, reaction extent x, and a step-by-step log. Copy the URL to share the exact setup.
The default example auto-loads N2O4 <=> 2NO2 at 25 °C, showing a modest forward shift. All calculations run in your browser only.
Reaction and initial conditions
Enable at least one reactant and one product. Units update automatically when you switch Kc ↔ Kp.
| Include | Species | Role | Coefficient | Initial |
|---|---|---|---|---|
Equilibrium constant and options
Use mol/L for Kc and bar for Kp.
Enter K at the temperature of interest. Temperature dependence is not modeled in this version.
Summary
How it is calculated
FAQ
What kinds of reactions can I solve with this tool?
It handles a single equilibrium reaction with up to four species, using Kc for solution equilibria or Kp for gas-phase equilibria. Multi-step or coupled equilibria are out of scope.
Why do I see errors about negative concentrations or no physical solution?
Some K values and initial conditions produce no non-negative equilibrium concentrations in the feasible interval, or the numeric solver may not find a root when the change is extreme. Adjust the starting concentrations or K and try again.
What is the 5% small-x approximation?
When the reaction extent x is small compared with initial concentrations, you can assume C0 ± x ≈ C0 to simplify algebra. This tool reports the maximum relative change and flags whether the 5% rule is satisfied.