Question detail
A reaction makes 40 cm3 of gas in 20 seconds. Which mean rate is correct?
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. 2 cm3/s
- B. 0.5 cm3/s
- C. 20 cm3/s
- D. 800 cm3/s
Answer
2 cm3/s. The product volume is divided by the time, so 40 cm3 ? 20 s = 2 cm3/s.
Explanation
2 cm3/s is correct because this question measures product formed as gas volume. The calculation is product volume divided by time; the other choices either invert the division or ignore the seconds unit.
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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