EnglandChemistry

3.3 Organic chemistry

16 dot points across 16 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How are alcohols made and what do they react to form?

Alcohols as products of fermentation and hydration of alkenes. Classification as primary, secondary and tertiary. Oxidation of alcohols with acidified potassium dichromate(VI) to aldehydes, carboxylic acids and ketones. Elimination to form alkenes. The biofuel debate.
A focused answer to the AQA A-Level Chemistry 3.3.5 specification points on alcohols. Covers fermentation and hydration routes, primary, secondary and tertiary classification, oxidation with acidified dichromate, dehydration to alkenes, and the ethanol-as-biofuel debate.
10 min answer →

How do carbonyl compounds react and how can you tell aldehydes from ketones?

Aldehydes and ketones as carbonyl compounds. Oxidation of aldehydes to carboxylic acids and the use of Tollens' and Fehling's reagents to distinguish them from ketones. Reduction with NaBH4 to alcohols. Nucleophilic addition of HCN to form hydroxynitriles and the production of a racemic mixture.
A focused answer to the AQA A-Level Chemistry 3.3.8 specification points on carbonyl compounds. Covers oxidation of aldehydes, distinguishing tests, reduction with NaBH4, and the nucleophilic addition of HCN with its mechanism and racemic outcome.
10 min answer →

Why are alkanes useful fuels and how do they react?

Alkanes as saturated hydrocarbons from crude oil, fractional distillation, cracking. Combustion of alkanes and the formation of pollutants. Free-radical substitution of alkanes by halogens, including initiation, propagation and termination.
A focused answer to the AQA A-Level Chemistry 3.3.2 specification points on alkanes. Covers fractional distillation and cracking of crude oil, complete and incomplete combustion, pollutants and catalytic converters, and the free-radical substitution mechanism.
10 min answer →

Why are alkenes so much more reactive than alkanes?

Alkenes as unsaturated hydrocarbons containing a C=C double bond. The bonding in a double bond as a pi bond. Electrophilic addition of alkenes with hydrogen halides, sulfuric acid and bromine. Markownikoff addition and carbocation stability. Addition polymerisation.
A focused answer to the AQA A-Level Chemistry 3.3.4 specification points on alkenes. Covers the C=C double bond and pi bonding, electrophilic addition with hydrogen halides, bromine and sulfuric acid, carbocation stability and Markownikoff addition, and addition polymerisation.
10 min answer →

How are amines made and why do they behave as bases and nucleophiles?

Amines as bases and nucleophiles. Preparation of aliphatic amines by reaction of halogenoalkanes with ammonia and by reduction of nitriles. Preparation of aromatic amines by reduction of nitro compounds. The relative base strength of ammonia, primary aliphatic and aromatic amines. Amines as nucleophiles in further substitution.
A focused answer to the AQA A-Level Chemistry 3.3.12 specification points on amines. Covers preparation of aliphatic and aromatic amines, their behaviour as bases, the order of base strength, and their reactions as nucleophiles.
10 min answer →

How do amino acids build proteins and how does DNA store and copy information?

Amino acids as compounds with both amine and carboxylic acid groups and their behaviour as zwitterions. Formation of proteins by condensation of amino acids and their hydrolysis. The structure of DNA nucleotides, base pairing by hydrogen bonding, and the action of cisplatin. Enzymes as biological catalysts with stereospecific active sites.
A focused answer to the AQA A-Level Chemistry 3.3.14 to 3.3.16 specification points on biological molecules. Covers amino acid structure and zwitterions, protein formation and hydrolysis, enzyme action, DNA nucleotides and base pairing, and the anticancer drug cisplatin.
11 min answer →

Why is benzene so stable and how does it react?

The structure of benzene and the delocalised model. Evidence for delocalisation from enthalpies of hydrogenation and bond lengths. Electrophilic substitution reactions of benzene, including nitration and Friedel-Crafts acylation, with mechanisms and the role of the catalyst.
A focused answer to the AQA A-Level Chemistry 3.3.11 specification points on aromatic chemistry. Covers the delocalised model of benzene, thermochemical and bond-length evidence for it, and the electrophilic substitution mechanisms of nitration and Friedel-Crafts acylation.
11 min answer →

How do carboxylic acids behave as acids and how are esters and acyl chlorides made?

Carboxylic acids as weak acids that react with carbonates. Esterification of carboxylic acids with alcohols and the uses and hydrolysis of esters. Acylation by acyl chlorides and acid anhydrides reacting with water, alcohols, ammonia and amines. The industrial advantages of using acid anhydrides.
A focused answer to the AQA A-Level Chemistry 3.3.9 and 3.3.10 specification points on carboxylic acids and their derivatives. Covers acidity, esterification and ester hydrolysis, acylation reactions of acyl chlorides and anhydrides, and why anhydrides are preferred industrially.
11 min answer →

How does chromatography separate and identify the components of a mixture?

Chromatography as a method of separation using a stationary and a mobile phase. Thin-layer and column chromatography and the calculation of Rf values. Gas chromatography and the meaning of retention time. The combination of gas chromatography with mass spectrometry for identification.
A focused answer to the AQA A-Level Chemistry 3.3.16 specification points on chromatography. Covers the principle of stationary and mobile phases, thin-layer and column chromatography, Rf value calculation, gas chromatography and retention time, and the use of GC-MS.
9 min answer →

How do halogenoalkanes react and why do they affect the ozone layer?

Nucleophilic substitution of halogenoalkanes by hydroxide, cyanide and ammonia. Elimination of halogenoalkanes to form alkenes. The effect of bond enthalpy on rate of hydrolysis. CFCs and the depletion of the ozone layer.
A focused answer to the AQA A-Level Chemistry 3.3.3 specification points on halogenoalkanes. Covers nucleophilic substitution with hydroxide, cyanide and ammonia, elimination to alkenes, how bond enthalpy controls hydrolysis rate, and the role of CFCs in ozone depletion.
10 min answer →

How do chemists name, classify and represent organic molecules unambiguously?

Nomenclature, functional groups and homologous series. Structural, displayed, skeletal and molecular formulae. Structural isomers, E-Z stereoisomers and the use of CIP priority. Reaction mechanisms, free radicals, nucleophiles and electrophiles, and curly arrows.
A focused answer to the AQA A-Level Chemistry 3.3.1 specification points on introductory organic chemistry. Covers IUPAC nomenclature, functional groups, homologous series, the four formula types, structural and E-Z isomerism, and the language of reaction mechanisms.
9 min answer →

How does NMR reveal the carbon and hydrogen environments in a molecule?

The use of carbon-13 and proton (high-resolution) NMR spectroscopy. The number of peaks and chemical shift indicating different environments. Integration giving the ratio of hydrogen atoms. Spin-spin splitting interpreted with the n+1 rule, and the use of TMS as a reference and deuterated solvents.
A focused answer to the AQA A-Level Chemistry 3.3.16 specification points on NMR spectroscopy. Covers carbon-13 and proton NMR, chemical shift and environments, integration, spin-spin splitting and the n+1 rule, and the roles of TMS and deuterated solvents.
11 min answer →

Why do some molecules exist as non-superimposable mirror images?

Optical isomerism as a form of stereoisomerism. The chiral centre and its four different groups. Optical isomers (enantiomers) as non-superimposable mirror images. The effect of enantiomers on plane-polarised light and the meaning of a racemic mixture.
A focused answer to the AQA A-Level Chemistry 3.3.7 specification points on optical isomerism. Covers chiral centres, enantiomers as non-superimposable mirror images, the rotation of plane-polarised light, and racemic mixtures from reaction mechanisms.
8 min answer →

How can you identify a functional group from simple test-tube reactions?

Tests for alkenes, alcohols, aldehydes and carboxylic acids. Use of bromine water, acidified potassium dichromate(VI), Fehling's and Tollens' reagents, and sodium carbonate. Determination of empirical and molecular formulae from combustion or composition data. The principle of mass spectrometry and infrared spectroscopy for structure determination.
A focused answer to the AQA A-Level Chemistry 3.3.6 specification points on organic analysis. Covers chemical tests for the main functional groups, identification of products, and the use of mass spectrometry and infrared spectroscopy to determine structure.
10 min answer →

How do you plan a multi-step synthesis between functional groups?

Synthetic routes for preparing one organic compound from another in several steps. Reagents and conditions for the interconversion of functional groups in aliphatic and aromatic chemistry. Practical techniques for organic preparation, including purification and the determination of percentage yield.
A focused answer to the AQA A-Level Chemistry 3.3.15 specification points on organic synthesis. Covers planning multi-step routes, the key reagents and conditions for functional-group interconversions, and practical preparation, purification and percentage-yield techniques.
10 min answer →

How do addition and condensation polymers differ and how can they be made more sustainable?

Addition polymers from alkenes. Condensation polymers, including polyesters and polyamides, from two monomers or one monomer with two functional groups. Identifying the repeating unit and the monomers. Hydrolysis of condensation polymers. Biodegradability and disposal of polymers.
A focused answer to the AQA A-Level Chemistry 3.3.13 specification points on polymers. Covers addition polymerisation of alkenes, condensation polyesters and polyamides, identifying repeat units and monomers, hydrolysis of condensation polymers, and the disposal and biodegradability of plastics.
10 min answer →