16.1 A2 Level

Alcohols

Cambridge A-Level Chemistry (9701) · Unit 16: Hydroxy compounds · 7 flashcards

Alcohols is topic 16.1 in the Cambridge A-Level Chemistry (9701) syllabus , positioned in Unit 16 — Hydroxy compounds . In one line: Tertiary alcohols cannot be oxidized because they lack a hydrogen atom bonded to the carbon atom that is also bonded to the -OH group, which is necessary for the oxidation reaction to occur. Oxidizing primary alcohols will yield aldehydes and carboxylic acids. Oxidizing secondary alcohols will yield ketones.

Marked as A2 Level: examined at A Level in Paper 4 (A Level Structured Questions) and Paper 5 (Planning, Analysis and Evaluation). It is not tested on the AS-only papers (Papers 1, 2 and 3).

The deck below contains 7 flashcards — 1 definition, 5 key concepts and 1 calculation — covering the precise wording mark schemes reward. Use the definition card to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.

Key definition

What type of alcohol (primary, secondary, or tertiary) cannot be oxidized

Tertiary alcohols cannot be oxidized because they lack a hydrogen atom bonded to the carbon atom that is also bonded to the -OH group, which is necessary for the oxidation reaction to occur. Oxidizing primary alcohols will yield aldehydes and carboxylic acids. Oxidizing secondary alcohols will yield ketones.

What the Cambridge 9701 syllabus says

Official 2025-2027 spec · A2 Level

These are the exact learning outcomes Cambridge sets for this topic. The candidate is expected to be able to do each of these on the relevant paper.

recall the reactions (reagents and conditions) by which alcohols can be produced: (a) electrophilic addition of steam to an alkene, H2O(g) and H3PO4 catalyst (b) reaction of alkenes with cold dilute acidified potassium manganate(VII) to form a diol (c) substitution of a halogenoalkane using NaOH(aq) and heat (d) reduction of an aldehyde or ketone using NaBH4 or LiAl H4 (e) reduction of a carboxylic acid using LiAl H4 (f) hydrolysis of an ester using dilute acid or dilute alkali and heat
describe: (a) the reaction with oxygen (combustion) (b) substitution to form halogenoalkanes, e.g. by reaction with HX(g); or with KCl and concentrated H2SO4 or concentrated H3PO4; or with PCl 3 and heat; or with PCl 5; or with SOCl 2 (c) the reaction with Na(s) (d) oxidation with acidified K2Cr2O7 or acidified KMnO4 to: (i) carbonyl compounds by distillation (ii) carboxylic acids by refluxing (primary alcohols give aldehydes which can be further oxidised to carboxylic acids, secondary alcohols give ketones, tertiary alcohols cannot be oxidised) (e) dehydration to an alkene, by using a heated catalyst, e.g. Al2O3 or a concentrated acid (f) formation of esters by reaction with carboxylic acids and concentrated H2SO4 as catalyst as exemplified by ethanol
deduce the presence of a CH3CH(OH)– group in an alcohol, CH3CH(OH)–R, from its reaction with alkaline I2(aq) to form a yellow precipitate of tri-iodomethane and an ion, RCO2 –
explain the acidity of alcohols compared with water

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 9701 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

diol reduction hydrolysis oxidation dehydration ester tri-iodomethane

Tips to avoid common mistakes in Alcohols

› Only primary and secondary alcohols react with acidified potassium dichromate(VI); alkenes, ketones, and tertiary alcohols do not.
› Construct balanced half-equations to determine electron transfer; remember one mole of dichromate(VI) ions gains six moles of electrons.
› Always check for chiral centers in isomerism questions; for instance, 2-methylbutanal has two optical isomers.
› Ensure the molecule contains the -CH(OH)CH3 or -COCH3 group at both ends to produce a dicarboxylic acid via the iodoform reaction.
› Draw the displayed formula of the ethanol product and label the specific hydrogen isotopes on the -CH2OH group to track their movement correctly.

Key Concept Flip

List the reagents and conditions required to produce an alcohol via electrophilic addition of steam to an alkene.

Answer Flip

The reagents and conditions required are steam (H₂O(g)) and a phosphoric acid catalyst (H₃PO₄). This process converts alkenes to alcohols by adding water across the double bond.

Key Concept Flip

What reagents and conditions are needed to reduce a carboxylic acid to a primary alcohol?

Answer Flip

The reducing agent is Lithium Aluminium Hydride (LiAlH₄). This reaction typically requires an anhydrous solvent, such as ether, to prevent the LiAlH₄ from reacting violently with water.

Definition Flip

What type of alcohol (primary, secondary, or tertiary) cannot be oxidized?

Answer Flip

Key Concept Flip

Outline the reaction, including reagents, conditions, and observations, used to test for the presence of a CH₃CH(OH)- group in an alcohol.

Answer Flip

Iodoform test. Reagents: alkaline iodine (I₂(aq) in NaOH(aq)). Observation: A positive result is indicated by the formation of a yellow precipitate of tri-iodomethane (CHI₃).

Calculation Flip

Write a balanced chemical equation for the complete combustion of ethanol.

Answer Flip

C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(g). Complete combustion requires sufficient oxygen to fully oxidize the alcohol to carbon dioxide and water.

Key Concept Flip

Describe how an alcohol can be dehydrated to form an alkene.

Answer Flip

Alcohols can be dehydrated using a heated catalyst, such as Al₂O₃ at high temperature, or by refluxing with a concentrated acid (

Example: concentrated H₂SO₄). This process eliminates water, forming a C=C double bond.

Key Concept Flip

Explain why alcohols are more acidic than water.

Answer Flip

Alcohols are actually LESS acidic than water. The alkyl group in an alcohol is electron-donating, which increases the electron density on the oxygen atom, making it less likely to donate a proton (H⁺).

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Key terms covered in this Alcohols deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

What type of alcohol (primary, secondary, or tertiary) cannot be oxidized

How to study this Alcohols deck

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