Explain how concentration affects collision frequency and rate.

In the subtopic Factors affecting reaction rate, this AQA A-Level Chemistry 7405 learning objective focuses on explain how concentration affects collision frequency and 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 concentration, rate. Collision frequency. means the number of collisions that occur per unit time between reacting particles, influencing the rate of reaction Avoid the mistake of students often confuse concentration with the total amount of substance, leading to incorrect conclusions about how concentration affects reaction rate; instead, to correctly explain how concentration affects collision frequency and rate, use the formula for collision frequency: collision frequency ∝ concentration. For example, if the concentration of reactants is doubled, the collision frequency also doubles, leading to an increased reaction rate. Therefore, if the initial concentration is 0.5 mol/dm³ and the new concentration is 1.0 mol/dm³, the substitution would be: collision frequency ∝ 1.0 mol/dm³ / 0.5 mol/dm³ = 2. The answer is that the collision frequency doubles, which increases the rate of reaction For exam answers, remember that increasing the concentration of reactants increases the number of particles in a given volume, leading to more frequent collisions and a higher reaction rate