What does the organic II and analysis block of Edexcel Chemistry cover?

This block is Topics 18 and 19 of the Edexcel 9CH0 specification: organic chemistry III (aromatics, carbonyls and carboxylic acids), organic nitrogen and polymers (amines, amino acids, proteins and polymers), organic synthesis and chirality, and modern analytical techniques (proton and carbon-13 NMR and chromatography).

How is the organic and analysis content examined in Edexcel Chemistry?

Expect mechanisms and reactions of benzene, carbonyls and acids, tests to distinguish functional groups (Tollens' and Fehling's for aldehydes), multi-step synthesis route questions, chirality and optical isomerism, and structure-determination questions that combine NMR, infrared and mass spectra. Spectroscopy interpretation is a major source of marks.

What is the key to answering NMR structure questions?

Count environments rather than atoms: carbon-13 NMR gives the number of carbon environments and proton NMR gives the number of hydrogen environments, with integration giving the ratio of protons and the n+1 splitting rule giving the number of neighbouring protons. Combine this with the molecular mass from mass spectrometry and the functional groups from infrared.

What is the single most common mistake in this block?

Saying ketones give a positive Tollens' or Fehling's test. Only aldehydes are oxidised by these reagents. Other frequent errors are drawing benzene with three localised double bonds to explain reactivity, confusing addition and condensation polymerisation, and counting atoms instead of environments in NMR.

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Edexcel A-Level Chemistry: Organic II and Analysis (Topics 18-19) overview

A deep-dive overview of Topics 18 and 19 of Edexcel A-Level Chemistry (9CH0): aromatics, carbonyls and acids, organic nitrogen and polymers, organic synthesis and chirality, and modern analytical techniques (NMR and chromatography).

Generated by Claude Opus 4.818 min read9CH0Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this block demands
Aromatics, carbonyls and acids
Nitrogen chemistry and polymers
Synthesis, chirality and analysis
How this block is examined
Check your knowledge

What this block demands

The final block of Edexcel A-Level Chemistry brings the organic course to its conclusion and adds the analytical techniques that tie everything together. It covers aromatic chemistry, carbonyls and acids, nitrogen chemistry and polymers, the planning of multi-step syntheses with attention to chirality, and the spectroscopy and chromatography used to determine structures. The examiners reward correct mechanisms, precise tests, well-planned synthetic routes, and confident spectral interpretation.

This guide walks through the topics in specification order and sets out the exam patterns Edexcel repeats. Each topic has a matching dot-point page with practice questions.

Aromatics, carbonyls and acids

Topic 18 (Organic chemistry III) covers the bonding in benzene (a delocalised pi system that gives stability and favours electrophilic substitution), the nucleophilic addition reactions of aldehydes and ketones, the test that distinguishes them (Tollens' and Fehling's oxidise aldehydes but not ketones), and the reactions of carboxylic acids and their derivatives (acyl chlorides, esters and amides interconverting by nucleophilic substitution).

Nitrogen chemistry and polymers

Topic 19 (Organic nitrogen and polymers) covers amines as organic bases and their preparation, amino acids as amphoteric zwitterions joining by peptide bonds to form proteins, and the formation, properties and disposal of addition polymers (inert, non-biodegradable) and condensation polymers (polyesters and polyamides that can be hydrolysed).

Synthesis, chirality and analysis

Organic synthesis and chirality covers optical isomerism (a chiral centre is a carbon with four different groups), the planning of multi-step routes by choosing reagents and conditions, and the importance of single enantiomers in pharmaceuticals. Modern analytical techniques covers proton and carbon-13 NMR (environments, chemical shift, integration and the n+1 rule), combining spectroscopic data, and chromatography (TLC, gas and HPLC).

How this block is examined

A typical Edexcel profile for Topics 18 and 19:

Mechanisms and reactions. Electrophilic substitution of benzene, nucleophilic addition to carbonyls, and acid-derivative interconversions.
Tests. Tollens' and Fehling's for aldehydes, and identifying functional groups.
Synthesis. Multi-step route questions choosing reagents and conditions, and reasoning about chirality.
Structure determination. Combining NMR, infrared and mass spectra to deduce a full structure, and interpreting chromatograms.

Check your knowledge

A mix of recall and application questions across Topics 18 and 19. Attempt them under timed conditions, then check against the solutions.

Explain why benzene undergoes electrophilic substitution rather than addition. (2 marks)
Describe a chemical test that distinguishes an aldehyde from a ketone. (2 marks)
Explain why amino acids exist as zwitterions. (2 marks)
State one reason condensation polymers are easier to dispose of than addition polymers. (2 marks)
State what is meant by a chiral centre. (1 mark)
A proton NMR peak appears as a triplet. State how many protons are on the neighbouring carbon. (1 mark)

Solutions

Q1: Benzene has a stable delocalised pi system of six electrons. Substitution preserves this stability, whereas addition would disrupt the delocalised ring, so electrophilic substitution is favoured.
Q2: Warm the compound with Tollens' reagent: an aldehyde produces a silver mirror, while a ketone gives no change (alternatively Fehling's solution gives a brick-red precipitate with an aldehyde only).
Q3: An amino acid has a basic amine group and an acidic carboxylic acid group; the $-COOH$ donates a proton to the $-NH_2$ , giving an ion with both a positive ( $-NH_3^+$ ) and a negative ( $-COO^-$ ) charge.
Q4: Condensation polymers contain ester or amide links that can be hydrolysed and broken down, whereas addition polymers have an inert, non-biodegradable carbon backbone.
Q5: A carbon atom bonded to four different groups.
Q6: Two (a triplet means $n+1 = 3$ , so $n = 2$ neighbouring protons).

Sources & how we know this

Pearson Edexcel A-Level Chemistry (9CH0) specification — Pearson Edexcel (2015)