O-LevelChemistryOrganic Chemistry5070/21 · May/June 2021 · Q310 Marks

Petroleum (crude oil) is a mixture of hydrocarbons.

(a)(i)Name the process used to separate petroleum (crude oil) into fractions.[1]
(a)(ii)Name one other fraction separated from petroleum (crude oil). Give a large-scale use for this fraction. fraction use[1]
(a)(iii)Petroleum (crude oil) does not contain enough of the fractions that contain smaller hydrocarbon molecules such as petrol (gasoline). Petroleum contains a high proportion of larger hydrocarbon molecules such as naphtha. Describe how the demand for smaller hydrocarbon molecules is satisfied.[2]
(b)The structure of chloroethene is shown. H | C / H H || C | Cl Chloroethene is the monomer used to make poly(chloroethene). Poly(chloroethene) is non-biodegradable.
(b)(i)Explain the meaning of the term non-biodegradable.[1]
(b)(ii)Describe one environmental problem caused by the disposal of non-biodegradable plastics.[1]
(b)(iii)Draw the partial structure of poly(chloroethene). Show at least two repeat units.[2]
(b)(iv)A factory uses 100 tonnes of chloroethene to make poly(chloroethene). Deduce the mass of poly(chloroethene) made. Assume the percentage yield is 100%. Explain your answer.[1]
(b)(v)Chloroethene reacts with hydrogen in the presence of a catalyst. Suggest the structure of the product of this reaction.[1]

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Mark scheme

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

3(a)(i) fractional distillation
3(a)(ii) Any one from: diesel - fuel for cars or lorries (1)
3(a)(ii) paraffin / kerosene – heating / cooking / aviation fuel (1)
3(a)(ii) bitumen – water proofing / roofing / road surfaces (1)
3(a)(ii) heating oil - fuel for heating (1)
3(a)(ii) lubricating or heavy oils – lubrication / fuels for ships (1)
3(a)(iii) cracking / heating strongly (in presence of a catalyst) (1)
3(a)(iii) large hydrocarbons or naphtha fraction broken down / (1)
3(b)(i) cannot be decayed / cannot be decomposed (by natural or bacterial action)
3(b)(ii) incineration causes poisonous gases / litter / plastic waste in the sea / killing animals / takes up space in landfill sites
3(b)(iii) ΗΗΗ Η -c-c-c-c- HCIH CI one repeat unit shown (1)
3(b)(iii) at least two repeat units and extension bonds at both ends (1)
3(b)(iv) 100 tonnes because it is addition polymerisation / it is an addition reaction / no other product is produced
3(b)(v) CH3CH2Cl

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