S3.2 Exam Practice
Functional Groups
Section B: Data Analysis
Calculator and Data Booklet permitted.
Question 1: Homologous Series Deduce
5 marksBoiling points of straight-chain alcohols:
| Alcohol | Formula | B.P. / °C |
|---|---|---|
| Methanol | CH₃OH | 65 |
| Ethanol | C₂H₅OH | 78 |
| Propan-1-ol | C₃H₇OH | 97 |
| Butan-1-ol | C₄H₉OH | 117 |
(a) State the general formula for alcohols. [1]
(b) Explain the trend in boiling points. [2]
(c) Explain why alcohols have higher boiling points than alkanes of similar molar mass. [2]
Show Mark Scheme
(a) CₙH₂ₙ₊₁OH [1]
(b) Boiling point increases with chain length [1]; longer chains have more London dispersion forces / greater surface area for intermolecular contact [1]
(c) Alcohols can form hydrogen bonds due to the O-H group [1]; hydrogen bonds are stronger than London forces, requiring more energy to break [1]
Question 2: Structural Isomerism Deduce
4 marks(a) Define structural isomers. [1]
(b) Draw and name all structural isomers of C₄H₁₀O that are alcohols. [2]
(c) State one isomer of C₄H₁₀O that is an ether, not an alcohol. [1]
Show Mark Scheme
(a) Molecules with the same molecular formula but different structural arrangements [1]
(b) Butan-1-ol, butan-2-ol, 2-methylpropan-1-ol, 2-methylpropan-2-ol [1] with correct structures [1]
(c) Diethyl ether (CH₃CH₂OCH₂CH₃) or methyl propyl ether [1]
Section C: Structured Questions
Show all working clearly.
Question 3: Functional Group Reactions State
5 marks(a) State the functional group in: (i) carboxylic acids, (ii) aldehydes, (iii) esters. [3]
(b) Write the equation for the combustion of ethanol. [1]
(c) State the test to distinguish between an aldehyde and a ketone. [1]
Show Mark Scheme
(a)(i) –COOH [1] (ii) –CHO [1] (iii) –COO– [1]
(b) C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O [1]
(c) Tollens' reagent (silver mirror test); aldehydes give a silver mirror, ketones do not [1]
Question 4: IUPAC Nomenclature State
4 marks(a) Name the following: (i) CH₃CH₂CH₂COOH, (ii) CH₃COCH₃, (iii) CH₃CH₂CHO. [3]
(b) State the type of reaction when an alcohol reacts with a carboxylic acid. [1]
Show Mark Scheme
(a)(i) Butanoic acid [1] (ii) Propanone [1] (iii) Propanal [1]
(b) Condensation (esterification) [1]
Question 5: Degree of Unsaturation HL Deduce
4 marks(a) Calculate the index of hydrogen deficiency (IHD) for C₆H₅NO₂. [1]
(b) Deduce what an IHD of 4 suggests about the structure. [1]
(c) State the reagent and observation to test for unsaturation. [2]
Show Mark Scheme
(a) IHD = (2×6 + 2 − 5 + 1) / 2 = 4 [1]
(b) Likely contains an aromatic ring (IHD = 4 = ring + 3 double bonds) [1]
(c) Bromine water [1]; decolourises from orange/brown to colourless if C=C present [1]
⚡ Try Exam Mode
Timed, one-question-at-a-time practice with a full score breakdown. Pick topics and test yourself under real exam conditions.
Start Exam Mode