Introduction to organic chemistryEdexcel A-Level Chemistry: Subtopic test

1. 1
   A chemist analyses a compound X from a sample of fuel. X is a hydrocarbon that contains 85.7% carbon and 14.3% hydrogen by mass, has a relative molecular mass of 84.0 and decolourises bromine water.

   (a)

   Which of these compounds is a hydrocarbon?

   [1 mark]

   • AC₄H₁₀
   • BC₂H₅Br
   • CC₂H₅OH
   • DCH₃COOH

   (b)

   X decolourises bromine water. To which homologous series does X belong, and what is its general formula?

   [1 mark]

   • AAlkane, CₙH₂ₙ₊₂
   • BHaloalkane, CₙH₂ₙ₊₁X
   • CAlkene, CₙH₂ₙ
   • DAlcohol, CₙH₂ₙ₊₁OH

   (c)

   Use the data to deduce the empirical formula and the molecular formula of X.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   Compound Y has the structural formula (CH₃)₂CHCH₂CH₃ and is found in petrol.

   (a)

   What is the IUPAC name of Y?

   [1 mark]

   • A3-methylbutane
   • B2-methylbutane
   • Cpentane
   • D2-ethylpropane

   (b)

   Which pair of compounds are both members of the same homologous series as Y?

   [1 mark]

   • AC₂H₄ and C₃H₆
   • BC₂H₅OH and C₃H₇OH
   • CC₂H₅Br and C₃H₇Br
   • DC₃H₈ and C₆H₁₄

   (c)

   Y reacts with chlorine in ultraviolet light to form a compound with the formula C₅H₁₁Cl. State the type of reaction and write the equation for the formation of C₅H₁₁Cl.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Organic chemists use IUPAC nomenclature so that every compound has a unique, systematic name.

   (a)

   Give the IUPAC names of (i) CH₃CH(OH)CH₂CH₃, (ii) (CH₃)₂C=CHCH₃ and (iii) CH₃CHBrCH₂CH₂CH₃.

   [3 marks]

   (b)

   A student names CH₃CH₂CH=CHCH₃ as pent-3-ene and CH₃CH(CH₃)CH₂CH₃ as 3-methylbutane. Explain the error in each name and give the correct name.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student revising reaction types is given six reactions: (i) CH₃CH=CH₂ + HBr → CH₃CHBrCH₃; (ii) CH₃CHBrCH₃ + OH⁻(aq) → CH₃CH(OH)CH₃ + Br⁻; (iii) CH₃CHBrCH₃ heated with ethanolic potassium hydroxide → CH₃CH=CH₂ + KBr + H₂O; (iv) CH₃CH₂OH + [O] → CH₃CHO + H₂O; (v) CH₃CHO + 2[H] → CH₃CH₂OH; (vi) n CH₃CH=CH₂ → poly(propene).

   (a)

   Classify each of the reactions (i) to (vi) as addition, elimination, substitution, oxidation, reduction or polymerisation, justifying each in terms of the change to the organic compound.

   [6 marks]

   (b)

   Explain why reactions (i) and (iii) can be described as the reverse of one another, why (iv) and (v) are opposite processes, and why (ii) can be called both substitution and hydrolysis.

   [6 marks]

   Total for question 4: 12 marks

End of questions