Question detail
Why can mass loss be used to measure rate in some reactions?
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. a gas product leaves the flask so the measured mass decreases over time
- B. all products are solids with no mass
- C. the balance measures temperature directly
- D. the reactants become heavier every second
Answer
a gas product leaves the flask so the measured mass decreases over time. This is correct for reactant used because the rate is found from mass loss or disappearance of reactant over time, divided by the time taken.
Explanation
a gas product leaves the flask so the measured mass decreases over time is the correct option. For this reactant used 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, 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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