Chemistry of carbon compounds: WAEC Chemistry Past Questions and Answers

What the WAEC syllabus covers in Chemistry of carbon compounds

Our summary: How organic compounds are classified and named, petroleum, isomerism, and the hydrocarbons, alkanols, alkanoic acids and esters.

• Classification (Broad classification into straight chain, branched chain, aromatic and alicyclic compounds.)
• Functional group (Systematic nomenclature of compounds with the following functional groups: alkanes, alkenes, alkynes, hydroxyl compounds (aliphatic and aromatic), alkanoic acids, alkyl alkanoates (esters and salts) and amines.)
• Separation and purification of organic compounds (Methods to be discussed should include: distillation; crystallization; drying and chromatography.)
• Petroleum/crude oil ((1) Composition and classification. (2) Fractional distillation and major products. (3) Cracking and reforming. (4) Petro-chemicals: sources; uses e.g. as starting materials of organic synthesis. (5) Quality of petrol, meaning of octane number and its importance to the petroleum industry.)
• Determination of empirical and molecular formulae and molecular structures of organic compounds
• General properties of organic compounds: homologous series ((1) Gradation in physical properties. (2) Effects on the physical properties by introduction of active groups into the inert alkane.)
• General properties of organic compounds: isomerism ((1) Examples should be limited to compounds having maximum of five carbon atoms. (2) Differences between structural and geometric/stereo isomerism.)
• Alkanes: sources, properties ((1) Laboratory and industrial preparations and other sources. (2) Nomenclature and structure. (3) Reactivity: (a) combustion; (b) substitution reactions; (c) cracking of large alkane molecules.)
• Alkanes: uses (As fuels, as starting materials for synthesis. Uses of haloalkanes and pollution effects.)
• Alkenes: sources and properties ((1) Laboratory preparation. (2) Nomenclature and structure. (3) Addition reactions with halogens, hydrogen, bromine water, hydrogen halides and acidified water. (4) Oxidation: hydroxylation with aqueous KMnO₄. (5) Polymerization.)
• Alkenes: uses
• Alkenes: laboratory detection (Use of reaction with Br₂/water, Br₂/CCl₄ and KMnO₄(aq) as means of characterizing alkenes.)
• Alkynes: sources, characteristic properties and uses ((1) Nomenclature and structure. (2) Industrial production of ethyne. (3) Uses of ethyne. (4) Distinguishing test between terminal and non-terminal alkynes. (5) Test to distinguish between alkane, alkene and alkyne.)
• Alkynes: chemical reactions (Chemical reactions: halogenation, combustion, hydration and hydrogenation.)
• Benzene: structure and physical properties (Resonance in benzene. Stability leading to substitution reactions.)
• Benzene: chemical properties ((1) Addition reactions: hydrogenation and halogenation (mechanism not required). (2) Compare reactions with those of alkenes.)
• Alkanols: sources, nomenclature and structure ((1) Laboratory preparation including hydration of alkenes. (2) Industrial and local production of ethanol including alcoholic beverages. (3) Harmful impurities and methods of purification should be mentioned. (4) Recognition of the structure of mono-, di- and triols.)
• Alkanols: classification (Primary, secondary and tertiary alkanols.)
• Alkanols: physical properties (Boiling point, solubility in water. Including hydrogen bonding effect.)
• Alkanols: chemical properties ((1) Reaction with: (a) Na; (b) alkanoic acids (esterification); (c) conc. H₂SO₄. (2) Oxidation by: (a) KMnO₄(aq); (b) K₂Cr₂O₇(aq); (c) I₂ in NaOH(aq).)
• Alkanols: laboratory test (Laboratory test for ethanol.)
• Alkanols: uses
• Alkanoic acids (Methanoic acid - insect bite. Ethanoic acid - vinegar.)
• Alkanoic acids: sources, nomenclature and structure (Recognition of mono and dioic acid.)
• Alkanoic acids: physical properties (Boiling point, solubility in water. Including hydrogen bonding effect.)
• Alkanoic acids: chemical properties (Acid properties only i.e. reactions with H₂O, NaOH, NH₃, NaHCO₃, Zn and Mg.)
• Alkanoic acids: laboratory test (Reaction with NaHCO₃, Na₂CO₃.)
• Alkanoic acids: uses (Uses of ethanoic and phenyl methanoic (benzoic) acids as examples of aliphatic and aromatic acids respectively.)
• Alkanoates as derivatives of alkanoic acids: sources, nomenclature, preparation and structure (Preparation of alkyl alkanoates (esters) from alkanoic acids.)
• Alkanoates: physical properties (Solubility, boiling and melting point.)
• Alkanoates: chemical properties (Hydrolysis of alkyl alkanoates (mechanism not required).)
• Alkanoates: uses (Uses of alkanoates to include production of soap, flavouring agent, plasticizers, as solvents and in perfumes.)

Syllabus content © The West African Examinations Council (WASSCE (harmonised West African syllabus)).