How Collision Theory Explains Rate
Part of Rates & Collision Theory — GCSE Chemistry
This how it works covers How Collision Theory Explains Rate within Rates & Collision Theory for GCSE Chemistry. Revise Rates & Collision Theory in Rates of Reaction for GCSE Chemistry with 20 exam-style questions and 16 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 4 of 13 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 13
Practice
20 questions
Recall
16 flashcards
⚙️ How Collision Theory Explains Rate
Collision theory is the underlying explanation for every factor that affects rate. To understand why a reaction speeds up or slows down, you must think about what happens at the particle level.
Two conditions must BOTH be met for a reaction to occur:
- Sufficient energy: The combined kinetic energy of the colliding particles must be at least equal to the activation energy (Ea). Activation energy is the minimum energy needed to break the bonds in the reactants and start the reaction. Collisions below this threshold simply bounce off — no reaction.
- Correct orientation: Particles must strike each other at the right angle so that reactive parts of the molecules can interact. A high-energy collision at the wrong angle still fails.
This is why increasing temperature is so powerful: it simultaneously increases both the frequency of collisions (particles move faster, so they meet more often) and the proportion of collisions with energy above Ea (the Maxwell-Boltzmann distribution shifts right). Both effects multiply together to increase rate dramatically.