Question detail
If 0.5 moles of a reactant are consumed in 10 seconds, what is the rate of the reaction?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
AS practical skills and required practical activities
Question
- A. 0.05 mol/s
- B. 0.1 mol/s (A-level cue 1b13da43 distractor 1)
- C. 0.2 mol/s (A-level cue 1b13da43 distractor 2)
- D. 0.5 mol/s (A-level cue 1b13da43 distractor 3)
Answer
0.05 mol/s
Explanation
The correct option is 0.05 mol/s. 0.05 mol/s is correct because it supports the objective: Measure reaction rates using appropriate methods.. The reasoning stays within AS apparatus and techniques 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
Incorrect Measurement of Reaction Rate
Students often confuse the method of measuring reaction rates, leading to incorrect calculations. For example, they might use the total time taken for a reaction instead of the change in concentration over time.
To accurately measure reaction rates, use the formula: rate = change in concentration / time. For instance, if the concentration of a reactant decreases from 0.5 mol/dm³ to 0.2 mol/dm³ in 10 seconds, substitute into the formula: rate = (0.5 - 0.2) mol/dm³ / 10 s = 0.03 mol/dm³/s. This shows the correct method for calculating the reaction rate.
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