Question detail
Why does the product-formed rate often decrease as the reaction continues?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Rate of reaction
Question
- A. reactant particles are used up so successful collisions become less frequent
- B. the product changes into a catalyst
- C. temperature must always fall to zero
- D. the graph gradient must become negative
Answer
reactant particles are used up so successful collisions become less frequent. This is correct for product formed because the rate is found from gas volume or precipitate/product formation over time, divided by the time taken.
Explanation
reactant particles are used up so successful collisions become less frequent is the correct option. For this product formed objective, mean rate equals the measured quantity change divided by time. The distractors either invert the calculation, use the wrong measured quantity, or ignore the time unit, so they do not answer the AQA Chemistry rate calculation accurately.
Common mistake
Confusing Rate Calculation
Students often confuse the formula for calculating the mean rate of reaction by using the quantity of reactant instead of the quantity of product formed.
Always ensure to use the quantity of product formed divided by the time taken when calculating the mean rate of reaction.
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