Below is a model containing reactants which will form the reaction: A₂ + B₂ --> 2 AB. In this case the model has been set so the activation energy is high. Try running the reaction with and without a catalyst to see the effect catalysts have on chemical reactions. Experimenting with the model: 1. Run the model to observe what happens without a catalyst. 2. Pause the model. 3. Add a few (3 - 4) catalyst atoms to the container by clicking the button. 4. Run the model again, and observe how the catalyst affects the reaction.