A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid - AQA - GCSE Chemistry - Question 9 - 2021 - Paper 2
Question 9
A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid.
The equation for the reaction is:
Zn(s... show full transcript
Worked Solution & Example Answer:A student investigated how a change in concentration affects the rate of the reaction between zinc powder and sulfuric acid - AQA - GCSE Chemistry - Question 9 - 2021 - Paper 2
Step 1
The student made an error in setting up the apparatus in Figure 8. What error did the student make?
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Answer
The delivery tube is placed in sulfuric acid instead of just being over it. This setup could prevent gas from escaping correctly.
Step 2
Explain why the lines of best fit on Figure 9 become horizontal.
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Answer
The lines become horizontal because the reaction has stopped. This occurs when the reactant, sulfuric acid, is completely used up.
Step 3
How does Figure 9 show that zinc powder reacts more slowly with 0.05 mol/dm³ sulfuric acid than with 0.10 mol/dm³ sulfuric acid?
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Answer
Figure 9 demonstrates that with 0.05 mol/dm³ sulfuric acid, the reaction progresses at a slower rate as indicated by a shallower slope compared to the steeper slope of the 0.10 mol/dm³ sulfuric acid line.
Step 4
Determine the rate of the reaction for 0.05 mol/dm³ sulfuric acid at 80 seconds.
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Answer
To find the rate, draw a tangent to the curve for the 0.05 mol/dm³ line at 80 seconds. Calculate the change in volume of gas collected from the graph to find the y-step, and the x-step will be 30 seconds. The rate can then be calculated as:
Rate=x-stepchange in volume
Substituting the values gives an answer to 2 significant figures.
Step 5
What is the most likely formula of the metal ions added? Tick (✓) one box.
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Answer
The most likely formula of the metal ions added is Cu²⁺.
