O-LevelChemistryMetals & Reactivity5070/21 · Oct/Nov 2016 · Q910 Marks

Tin and silver are metals.

(a)State two properties which are characteristic of most metals.[2]
(b)Draw a labelled diagram to show how a tin rod can be electroplated with silver.[3]
(c)A 9.50 g sample of a chloride of tin contains 5.95 g of tin. Deduce the empirical formula of this chloride of tin.[2]
(d)Tin(II) oxide reacts with oxygen to form tin(IV) oxide. 2SnO + O2 → 2SnO2 tin(II) oxide tin(IV) oxide When a sample of 13.5g of tin(II) oxide is reacted with oxygen, 12.7g of tin(IV) oxide is formed. Calculate the percentage yield of tin(IV) oxide.[3]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2016). The mark or mark type is shown in brackets.

[1] One mark each for any two suitable properties e.g.: • shiny • conducts heat/conducts electricity • malleable • ductile
[1] 2 electrodes dipping into liquid and connected to a power supply (1)
[1] electrolyte labelled as aqueous silver ions, soluble silver compound or named soluble silver compound/silver nitrate solution (1)
[1] silver anode/silver positive electrode AND tin cathode/tin negative electrode (1)
[1] mol Sn = 5.95 / 119
[1] mol Cl = 3.55 / 35.5 dividing masses by correct atomic masses (1)
[1] (mol Sn = 0.05 and mol Cl = 0.1) formula is SnCl2 (1)
[1] mol tin(II) oxide = 13.5 / 135 OR 0.10 mol (1)
[1] mass tin(IV) oxide expected = 0.10 × 151 = 15.1g (1)
[1] % yield = 12.7 / 15.1 × 100 = 84% (1)

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