O-LevelChemistryOrganic Chemistry5070/21 · May/June 2019 · Q1010 Marks
Cyclobutane and butene are both hydrocarbons. [Figure 10.1]
- (a)What is meant by the term hydrocarbon?[1]
- (b)Explain why cyclobutane and butene are isomers.[1]
- (c)Cyclobutane is saturated and butene is unsaturated. Describe a chemical test that can distinguish cyclobutane from butene. test result for cyclobutane result for butene[3]
- (d)Calculate the percentage by mass of carbon in butene.[2]
- (e)(i)Ethene can be converted into ethanoic acid in a two-step process. [Figure 10.2] Identify compound X.[1]
- (e)(ii)Identify the reagent used in step 1.[1]
- (e)(iii)Identify the reagent used in step 2.[1]
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 (May/June 2019). The mark or mark type is shown in brackets.
- [1] contains only hydrogen and carbon (1)
- [1] same molecular formula but different structures (1)
- [3] test: (aqueous) bromine (1)
- [3] cyclobutane: stays orange / no change (1)
- [3] butene: goes colourless (1)
- [2] M_r = 56 (1)
- [2] % = 85.7 / 86 (1)
- [1] ethanol / CH₃CH₂OH / C₂H₅OH (1)
- [1] steam (1)
- [1] (acidified) potassium manganate(VII) (1)
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