GCSE Chemistry - Factors Affecting Rate of Reaction & Collision Theory (2026/27 exams)

Explanation of collision theory, which states that particles must collide with sufficient activation energy to react. The reaction rate depends on the frequency of collisions and the energy levels of the particles.

Increasing temperature makes particles move faster, leading to more frequent collisions and a higher likelihood that particles exceed the activation energy.

Both concentration (in solutions) and pressure (in gases) relate to particle density per unit volume. Higher density increases the frequency of collisions, thereby increasing the reaction rate.

Increased surface area, such as using powder instead of solid blocks, provides more space for reactants to collide, resulting in a faster reaction rate.

Catalysts speed up reactions by lowering the activation energy through an alternative pathway without being consumed. Common examples include transition metals and biological enzymes.