Alkanes (Edexcel International A Level Chemistry)

Exam Questions

33 mins10 questions
11 mark

All alkanes have the same

  • empirical formula

  • general formula

  • molecular formula

  • structural formula

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21 mark

A single molecule of decane, C10H22 , is cracked.

Which of these mixtures could not be formed?

  • pentene and pentane

  • ethene, butene and butane

  • propene, propane and butene

  • hexene and propane

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31 mark

Which pollutant cannot form when alkane fuels are burned in car engines?

  • hydrogen chloride

  • sulfur dioxide

  • carbon particulates

  • carbon monoxide

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1a1 mark

Ethane reacts with bromine in the presence of ultraviolet radiation.

a)
What is the equation for the reaction?

  • C2H6 + Br2 → C2H4Br2 + H2

  • C2H6 + Br2 → C2H5Br + HBr

  • C2H6 + Br2 → 2CH3Br

  •  C2H6 + Br2 → CH4 + CH2Br2

1b1 mark
b)
The ultraviolet radiation is needed for
(1)
  A homolytic breaking of a Br–Br bond
  B heterolytic breaking of a Br–Br bond
  C homolytic breaking of a C–H bond
  D heterolytic breaking of a C–H bond

  • homolytic breaking of a Br–Br bond

  •  heterolytic breaking of a Br–Br bond

  • homolytic breaking of a C–H bond

  • heterolytic breaking of a C–H bond

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2a1 mark

Methane reacts with excess chlorine in UV light.

a)

Which process occurs in the initiation step?

(1)

q10a-paper-1-oct-2021-edexcel-ial-chemistry

    2b1 mark
    b)

    Which of these molecules could not be formed in a termination step?

    • C2H6

    • CH3Cl

    • CH2Cl2

    • HCl

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    3
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    1 mark

    When C20H42 is cracked, each molecule produces one molecule of ethene, one molecule of butane and two molecules of hydrocarbon E.

    What is the molecular formula of E?

    • C7H13   

    • C7H14

    • C14H26

    • C14H28

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    41 mark

    Petrol, bioethanol and hydrogen are fuels.

    All three of these fuels

    • burn to produce greenhouse gases

    • are overall carbon neutral

    • are overall sustainable

    • biodegrade rapidly

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    5a1 mark

    Cyclopentane undergoes free radical substitution with bromine.

    a)
    Which of these is an overall equation for this reaction?
    • C5H8 + Br2 → C5H8Br2

    • C5H10 + Br2 → C5H10Br2

    • C5H10 + Br2 → C5H8Br2 + H2

    • C5H10 + Br2 → C5H9Br + HBr

    5b1 mark
    b)
    Which statement is not correct about this reaction system?
    • only the initiation step involves homolytic bond fission

    • only some bromine is converted to free radicals in the initiation step

    • propagation forms more product than termination

    • further substitution reactions are likely to occur

    5c1 mark
    c)
    Which free radical is least likely to form in a propagation step in this reaction system?
    • C5straight H subscript 9 superscript •

    • Bstraight r to the power of •

    • C5H8Bstraight r to the power of •

    • straight H to the power of •

    5d1 mark
    d)
    Which alkane could be formed in a termination step in this reaction system?
       
    q16d-paper-1-jan-2021-edexcel-ial-chemistry

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