Rates of reaction is about how fast a reaction goes and why. You read the speed from a graph or table, you compare what changed it, and you explain the change with particles.
This cluster is part of the SPM Science learning guide. Each lesson has an original worked example and a self-check.
What does this area cover?
The first lesson reads the shape of a rate graph. The second compares concentration, temperature, surface area and a catalyst in fair tests. The third explains each factor using collisions between particles, and the fourth calculates an average rate from a supplied table.
How do the parts connect?
The four lessons form a loop. A graph shows that something changed, the fair test says what caused it, the collision idea explains why, and the calculation puts a number on how much.
| Lesson | Skill | Link to the next |
|---|---|---|
| Reading rate graphs | Read steepness and plateau | Raises the question of cause |
| Comparing factors | Fair tests | Needs a reason |
| Collision ideas | Particle explanation | Adds the numbers |
| Calculating a rate | Change ÷ time | Closes the loop |
A short orienting example
A table shows 0 cm³ of gas at 0 s and 30 cm³ at 20 s. The average rate over those 20 s is 30 ÷ 20 = 1.5 cm³ per second.
A second experiment gives 30 cm³ in 40 s, so its rate is 30 ÷ 40 = 0.75 cm³ per second. The first reaction is twice as fast. The reasons for the difference belong to the other three lessons.
Who should start where?
If graphs still confuse you, begin with the first lesson. If you can calculate but lose marks on explanation, go to the collision lesson. When you want to check everything together, use the rates of reaction practice set.
The graph evidence and fair-comparison lab helps you practise comparing results fairly. To work through the cluster with a teacher, see online one-to-one Science tuition.