Collision Theory Simulator
Watch molecules collide and see why only fast, well-oriented collisions react.
About the Collision Theory Simulator
Free collision theory simulation. Watch particles collide, count effective versus ineffective collisions, and see how energy and orientation decide whether a reaction happens. Built for reactions & kinetics, the collision theory 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 molecules collide and see why only fast, well-oriented collisions react. 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 Collision Theory Simulator
- Use the controls to change Temperature, Activation energy, Orientation tolerance. The simulation reacts instantly.
- Press "Pause", "Reset counters" 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
- Raise the temperature.
- Narrow the orientation tolerance.
- Lower the activation energy.
- Watch the success rate.
Key ideas you can learn
- A collision must have enough energy (at least the activation energy) to react.
- The particles must also hit in the right orientation.
- Most collisions are ineffective, which is why reactions take time.
Where this is used in the real world
Collision theory explains why refrigeration slows food spoilage and why catalysts and mixing speed up reactions.
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
What is collision theory?
The idea that particles must collide with enough energy and in the right orientation for a reaction to occur.
Why do most collisions not lead to a reaction?
Most collisions are too weak, or the molecules are the wrong way round, so they simply bounce apart.
Is the Collision Theory 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 Collision Theory 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.