O-LevelChemistryOrganic Chemistry5070/22 · Oct/Nov 2021 · Q810 Marks

The structure of an organic compound, T, is shown. H H c=c H CH2OH [Figure 8.1]

(a)Deduce the molecular formula of compound T.[1]
(b)Compound T is a colourless liquid. State the colour change when excess compound T is added to aqueous bromine. from to[1]
(c)Compound T can be oxidised to a carboxylic acid. Suggest a suitable oxidising agent for this reaction.[1]
(d)Compound T can be polymerised. Draw the partial structure of the polymer of compound T. Show two repeat units.[2]
(e)Compound T reacts with methanoic acid, HCOOH, to form an ester. Complete the structure of this ester to show all the atoms and all the bonds. H H c=c H C H H [Figure 8.2][1]
(f)(i)Methanoic acid is a weak acid. Hydrochloric acid is a strong acid. Give the formula of the positive ion that is present in all acids.[1]
(f)(ii)Explain why the rate of reaction of 1.0mol/dm³ methanoic acid with magnesium is less than the rate of reaction of 1.0mol/dm³ hydrochloric acid with magnesium.[1]
(g)Construct the equation for the reaction of methanoic acid with magnesium.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.

[1] C3H6O
[1] orange to colourless
[1] potassium manganate(VII)
[2] H H2COH H H2COH
- C - C - C - C - (2 marks)
H H H H
if 2 marks not scored 1 mark for
- C - C - C - C -
[1] completed with
O-C-H
[1] H+
[1] methanoic acid has a lower concentration of H+ ions / hydrochloric acid has a higher concentration of H+ ions
[2] 2HCOOH + Mg → (HCOO)2Mg + H2 (2)
if two marks not scored 1 mark for (HCOO)2Mg

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