Kinetics and Collision Theory Sandbox

Instructions

A and B react only when they collide hard enough. Change the temperature, the concentration and the activation energy, add a catalyst, and watch the rate of successful collisions and the concentration graph respond.

  1. Change one variable at a time: temperature, concentration, activation energy, or catalyst.
  2. Compare successful collisions with the concentration graph.
  3. Use the controls to pause, reset, and compare runs. Explain which changes affect the reaction rate.

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A + B → C + D in one step. Each particle of A stands for 0.01 M. Energies are scaled down so reactions happen in seconds.

2. Watch the particles

The reaction box

Time
[A] = [B]
A-B collisions
Successful
Success rate
Reaction rate

Collisions and rates are per second over the last 5 s.

3. Read the graph

Concentration vs. time

Start a new run to keep this one on the graph for comparison (up to 3).

4. Look at the energy

Why most collisions just bounce

Energy profile: A and B must climb the barrier to become C and D.
Collision energies: the curve is collision theory, the bars are this run. Only the shaded part reacts.

5. Check your thinking

Test each idea in the box

6. Make sense of it

What changes the rate?

Run the default, then change one condition at a time and start a new run, so the earlier runs stay on the graph to compare.

Which change sped up the reaction the most? How did it change the number of collisions, and the fraction that were successful? Why does the graph level off?

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