O-LevelChemistryAcids, Bases & Salts5070/21 · Oct/Nov 2019 · Q36 Marks
Water can be removed from aqueous copper(II) sulfate by distillation.
- (a)Describe how and explain why water can be separated from aqueous copper(II) sulfate by distillation. In your answer include a description of distillation. You may draw a labelled diagram.[3]
- (b)Copper(II) sulfate can be prepared by heating excess copper(II) oxide with dilute sulfuric acid. CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l) What method is used to separate excess copper(II) oxide from the reaction mixture?[1]
- (c)A copper compound contains 21.09% copper, 43.82% caesium and 35.09% chlorine by mass. Use this information to deduce the empirical formula of this copper compound. empirical formula ................................................................................................................ [2][2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.
- 3(a) Any three from:
- (property on which distillation) depends is the boiling point / copper(II) sulfate has higher boiling point than water / ORA (1)
- idea of distillation apparatus, e.g. flask connected to condenser (1)
- flask or solution heated (1)
- idea that only water vaporised (when flask heated) (1)
- water vapour converted to (liquid) water (in condenser) (1)
- 3(b) filtration
- 3(c) Cu Cs Cl
- 21.09 43.82 35.09
- 64 133 35.5
- OR
- Cu = 0.33 Cs = 0.33 Cl= 0.99 (1)
- CuCsCl3 (1)
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