4.1. Electrolysis
A subsection of Chemistry, 0620, through 4. Electrochemistry
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Copper(sulfate crystals, CuSO4.5H2O, are hydrated. Copper(sulfate crystals are made by reacting copper(carbonate with dilute sulfuricacid. The equation for the overall process is shown. CuCO3 + H2SO4 + 4H2O CuSO4.5H2O + CO2 step 1 Powdered solid copper(carbonate is added to 50.0 cm3 of 0.05 mol / dm3 sulfuricacid until the copper(carbonate is in excess. step 2 The excess of copper(carbonate is separated from the aqueous copper(sulfate. step 3 The aqueous copper(sulfate is heated until the solution is saturated. step 4 The solution is allowed to cool and crystallise. step 5 The crystals are removed and dried. Calculate the maximum mass of the copper(sulfate crystals, CuSO4.5H2O, that can form using the following steps. ● ● Calculate the number of moles of H2SO4 in 50.0 cm3 of 0.05 mol / dm3 H2SO4.  mol ● ● Determine the number of moles of CuSO4.5H2O that can form.  mol ● ● The Mr of CuSO4.5H2O is 250. Calculate the maximum mass of CuSO4.5H2O that can form.  g  Steps 1–5 were done correctly but the mass of crystals obtained was less than the maximum mass. Explain why. State two observations that would indicate that the copper(carbonate is in excess in step1.  When the reaction in step1 is done using lumps of copper(carbonate instead of powder, the rate of reaction decreases. All other conditions are kept the same. Give a reason for this. Explain your answer in terms of particles. Name a different substance, other than copper(carbonate, that could be added to dilute sulfuricacid to produce copper(sulfate in step1. Name the process used to separate the aqueous copper(sulfate from the excess of copper(carbonate in step2. The solution of aqueous copper(sulfate was heated until it was saturated in step3. Suggest what is meant by the term saturated solution. What evidence would show that the solution was saturated in step3? Why should the aqueous copper(sulfate not be heated to dryness in step3? 
0620_s19_qp_42
THEORY
2019
Paper 4, Variant 2
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