Chapter summary
Rate of Reactions, at a glance
Explain why reactions speed up, and read what a progress graph actually proves.
O-Level 6092 (2026) / SEC G3 K324 (2027)
Quick revision
Revisit the essentials, then return to an explanation when you need it.
| Term | Definition to write |
|---|---|
| Rate of reaction | The change in the amount (or concentration) of a reactant or product per unit time. |
| Effective collision | A collision between reacting particles that have energy equal to or greater than the activation energy, so that they react. |
Pure only
| Term | Definition to write |
|---|---|
| Catalyst | A substance that increases the rate of a reaction and remains chemically unchanged at the end of the reaction. |
| Enzyme | A biological catalyst (a protein). It is denatured at high temperatures. |
Rate describes change per unit time. Concentration, pressure, temperature and exposed surface area affect successful collisions. On a progress graph, slope indicates rate and the final level indicates measured amount.
Pure only
Pure: a catalyst lowers the activation barrier and is regenerated. A fair investigation changes one variable, controls alternatives and states how data will be analysed.
Quick recall
Why does increasing the concentration of an acid increase the rate of its reaction with magnesium?