Explain how pressure affects gas reaction rate.

In the subtopic Factors affecting reaction rate, this AQA A-Level Chemistry 7405 learning objective focuses on explain how pressure affects gas reaction rate. It belongs to Kinetics, so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include pressure, rate. Activation energy. means the minimum energy required for a chemical reaction to occur Avoid the mistake of students often think that increasing pressure always increases the reaction rate for gases without considering the volume change; instead, to explain how pressure affects gas reaction rate, use the formula: Rate ∝ Collision Frequency. When pressure increases, the volume decreases, leading to more frequent collisions. For example, if the pressure is doubled in a fixed volume, the number of gas particles per unit volume increases, thus increasing the collision frequency and the reaction rate. Therefore, if the initial pressure is P1 and the final pressure is P2, the relationship can be expressed as: Rate2 = Rate1 × (P2/P1). This shows that the reaction rate increases with pressure, provided the volume remains constant For exam answers, remember that increasing pressure in a gas reaction increases the rate by reducing the volume, leading to more frequent collisions