Chemical Equilibrium Simulator
Watch the forward and reverse reactions balance and apply Le Chatelier's principle.
About the Chemical Equilibrium Simulator
Free chemical equilibrium simulation for A ⇌ B. Watch forward and reverse rates balance, disturb the system, and see how it shifts. Great for Le Chatelier's principle. Built for reactions & kinetics, the chemical equilibrium simulator runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Watch the forward and reverse reactions balance and apply Le Chatelier's principle. Use it to explore reactions & kinetics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Chemical Equilibrium Simulator
- Use the controls to change Forward rate constant kf, Reverse rate constant kr, Disturb the system. The simulation reacts instantly.
- Press "+ 40 A", "+ 40 B", "− 40 B", "Restart" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Add 40 A and watch the shift.
- Remove product.
- Change kf and kr.
- Wait for equilibrium.
Key ideas you can learn
- At equilibrium the forward and reverse rates are equal, but the reactions never stop.
- Adding reactant pushes the system toward products, and removing product does the same.
- K = [B] / [A] at equilibrium tells you which side is favoured.
Where this is used in the real world
Equilibrium controls ammonia production for fertiliser, blood buffering in your body and ocean chemistry.
Who is this simulation for?
Students learning reaction rates, equilibrium and equations, and teachers who want a visual way to explain what happens to particles.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
Does the reaction stop at equilibrium?
No. Both reactions carry on at the same rate, so the amounts stay constant. This is called dynamic equilibrium.
What does Le Chatelier's principle say?
If you disturb a system at equilibrium, it shifts in the direction that partly counteracts the disturbance.
Is the Chemical Equilibrium Simulator free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Chemical Equilibrium Simulator work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.