This question is about zinc and compounds of zinc - AQA - GCSE Chemistry - Question 4 - 2022 - Paper 1
Question 4
This question is about zinc and compounds of zinc.
A student produces pure crystals of zinc chloride by reacting zinc oxide with hydrochloric acid.
The equation fo... show full transcript
Worked Solution & Example Answer:This question is about zinc and compounds of zinc - AQA - GCSE Chemistry - Question 4 - 2022 - Paper 1
Step 1
Give one observation that the student could make to show that the zinc oxide is in excess.
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Answer
The student could observe that excess zinc oxide solid remains in the reaction mixture after the hydrochloric acid is fully reacted.
Step 2
Why is excess zinc oxide used rather than excess hydrochloric acid?
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Excess zinc oxide can be filtered off, making it easier to separate the solid from the solution, ensuring that all hydrochloric acid is used efficiently.
Step 3
Name one other compound that the student could add to hydrochloric acid to produce zinc chloride.
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The student could add zinc hydroxide (Zn(OH)₂) or zinc carbonate (ZnCO₃) to hydrochloric acid to produce zinc chloride.
Step 4
Describe how the student should obtain crystals of zinc chloride from a solution of zinc chloride.
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The student should heat the solution until the crystallization point is reached, allowing the solution to reduce in volume. After crystals start to form, allow the solution to cool and then leave it to crystallize fully.
Step 5
Complete the ionic equation for this reaction.
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Answer
Zn + Cu²⁺ → Zn²⁺ + Cu
Step 6
Why is zinc described as being oxidised in this reaction?
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Zinc is described as being oxidised in this reaction because it loses electrons to form Zn²⁺ ions.
Step 7
Complete Figure 7 to show how zinc, copper and another substance can be used to light a lamp.
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The diagram should illustrate a solution in a container, with a zinc electrode and a copper electrode both inserted into the solution. The circuit should be complete, with a designated electrolyte in the solution and a label for the lamp.
