Question detail
A reaction occurs between reactants A and B in a solution. If the concentration of A is increased from 0.5 mol/dm³ to 1.0 mol/dm³, how does this affect the collision frequency and rate of the reaction? Assume the reaction is first order with respect to A. Calculate the new rate if the initial rate was 0.2 mol/dm³/s.
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At a glance
Question
Type
exam_style
Style
Topic
Kinetics
Question
A reaction occurs between reactants A and B in a solution. If the concentration of A is increased from 0.5 mol/dm³ to 1.0 mol/dm³, how does this affect the collision frequency and rate of the reaction? Assume the reaction is first order with respect to A. Calculate the new rate if the initial rate was 0.2 mol/dm³/s.
Answer
The new rate of the reaction is 0.4 mol/dm³/s. This answer is anchored to Factors affecting reaction rate. This version is uniquely anchored to Factors affecting reaction rate. Retrieval anchor: A-level cue 0dcba8f0.
Explanation
The new rate of the reaction is 0.4 mol/dm³/s. This answer is anchored to Factors affecting reaction rate. is correct because it supports the objective: Explain how concentration affects collision frequency and rate.. The reasoning stays within Factors affecting reaction rate and avoids drifting into a similar A-Level Chemistry idea. This item is treated as conceptual revision rather than a formal calculation item because the validated answer is an explanation or option choice, not a worked numerical response.
Common mistake
Misunderstanding Concentration Effects
Students often confuse concentration with the total amount of substance, leading to incorrect conclusions about how concentration affects reaction rate.
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.
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