Question detail

A reaction uses 30 g of reactant in 10 seconds. What is the mean rate of reactant use?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Rate of reaction

Question

A. 3 g/s
B. 0.33 g/s
C. 20 g/s
D. 300 g/s

Answer

3 g/s. The quantity of reactant used is divided by time: 30 g ? 10 s = 3 g/s.

Explanation

3 g/s is correct because the question measures reactant used up, not product made. The rate is calculated from the mass of reactant used divided by the time taken.

Common mistake

Confusing Rate Calculation

Students often confuse the formula for calculating the mean rate of reaction, mistakenly using the time taken as the numerator instead of the quantity of reactant used.

Remember that the mean rate of reaction is calculated by dividing the quantity of reactant used by the time taken. Ensure you set up the formula correctly as mean rate = quantity of reactant used / time.

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