Making soluble salts (except sodium, potassium and ammonium salts)
2 marks · NormalDescribe how you would prepare pure, hydrated zinc sulfate crystals starting from zinc oxide and dilute sulfuric acid.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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Also accept: Heat acid, add excess zinc oxide, filter, evaporate to crystallisation, cool, dry crystals
Common mistakes: Evaporate to dryness; Do not mention adding excess solid; Leave out filtration
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Marking points
M1 · 1 mark · Add excess zinc oxide to warm dilute sulfuric acid (until no more reacts)
M2 · 1 mark · Filter off unreacted solid; heat filtrate gently to crystallisation, then cool to allow crystals to form (or equivalent description)
Worked solution
Add excess zinc oxide to warm dilute sulfuric acid and stir until no more zinc oxide dissolves.
Filter off the unreacted solid. Heat the filtrate gently until crystals start to form on a glass rod, then allow to cool.
Remove and dry the crystals.