What is the difference between an alcohol and a phenol?

In an alcohol, the hydroxyl (–OH) group is attached to a saturated carbon atom (part of an alkyl group). In a phenol, the –OH group is attached directly to a carbon atom within a benzene ring. This difference leads to significantly different chemical properties, particularly in terms of acidity.

Can I use acidified potassium manganate(VII) to oxidise alcohols?

Yes, potassium manganate(VII) ($KMnO_4$) is a powerful oxidising agent and will oxidise primary and secondary alcohols. The colour change is from purple ($MnO_4^-$) to colourless ($Mn^{2+}$). However, it is less selective than dichromate(VI) and can easily cause cleavage of C-C bonds, especially under harsh conditions. For A-Level purposes, acidified potassium dichromate(VI) is the standard reagent you should refer to unless specified otherwise.

Why is a catalyst needed for esterification?

Esterification is a slow, reversible reaction. The strong acid catalyst (e.g., concentrated $H_2SO_4$) serves two purposes: it speeds up both the forward and reverse reactions, allowing equilibrium to be reached faster. It also acts as a dehydrating agent, removing the water produced, which shifts the equilibrium position to the right (according to Le Chatelier's principle), increasing the yield of the ester.

Where can I learn Alcohols for Cambridge 9701?

This free lesson on MarkScheme covers syllabus point 16.1 (Alcohols) for Cambridge A-Level Chemistry. It includes visual revision, key points, and links to real past-paper questions with mark-scheme marking at markscheme.app/courses/9701/16-1-alcohols.

Is Alcohols (16.1) on 9701 free to study?

Yes. The Chemistry 9701 course on MarkScheme is 100% free — including premium visual lessons, exam tips, and past-paper marking. No paywall for Alcohols.

How do I revise Alcohols for 9701 exams?

Start with the visual steps on this page, note the key exam points, then attempt a 9701 past-paper question on Alcohols using MarkScheme's /mark tool. Mark strictly against the official scheme and re-read any marks you lost.

Alcohols 9701 — Free A-Level Chemistry

Alcohols

Alcohols are a homologous series of organic compounds characterised by the presence of one or more hydroxyl (–OH) functional groups. Their general formula is $C_nH_{2n+1}OH$ . They are incredibly versatile and participate in a wide range of reactions, making them important intermediates in organic synthesis and widely used as solvents, fuels, and in beverages.

BY THE END, YOU CAN…

1Classify alcohols as primary, secondary, or tertiary based on their structure.
2Describe the oxidation of alcohols using acidified potassium dichromate(VI), predicting the products and stating the conditions for controlling the oxidation of primary alcohols.
3Explain the relative resistance to oxidation of primary, secondary, and tertiary alcohols.
4Describe the esterification of alcohols with carboxylic acids and the dehydration of alcohols to form alkenes, including reagents and conditions.

In simple terms

A friendly intro before the formal notes — no formulas yet.

Alcohols: The Reactive Hydroxyl

Alcohols are organic molecules containing a hydroxyl (–OH) group. Their classification as primary, secondary, or tertiary dictates how they react, particularly in oxidation reactions.

THINK OF IT LIKE…

Think of alcohols as different types of workshops. A primary alcohol is a simple workshop that can be upgraded in two stages (first to an aldehyde, then to a carboxylic acid). A secondary alcohol is a more specialised workshop that can only be upgraded once (to a ketone). A tertiary alcohol is a finished, custom-built workshop that can't be upgraded without being completely dismantled (resisting oxidation).

1
Alcohols contain –OH; primary, secondary, tertiary classification.
2
Oxidation: primary → aldehyde → carboxylic acid; secondary → ketone.
3
Tertiary alcohols resist oxidation without C–C cleavage.
4
Esterification: alcohol + carboxylic acid ⇌ ester + water (acid catalyst).

Explore the concept

Use the live diagram and synced steps — play it or tap a step card to walk through.

Key formulas

Tap any symbol to reveal exactly what it means and its units.

$Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^- \rightarrow 2Cr^{3+}(aq) + 7H_2O(l)$

$\text{Carboxylic Acid} + \text{Alcohol} \rightleftharpoons \text{Ester} + \text{Water} \\ \text{R-COOH} + \text{R'-OH} \xrightarrow{\text{conc. } H_2SO_4, \, \Delta} \text{R-COO-R'} + H_2O$

Full topic notes

Formal explanation with the rigour you need for the exam.

Classification of Alcohols

The reactivity of an alcohol is heavily influenced by its structure. We classify alcohols based on the number of alkyl groups attached to the 'carbinol carbon' – the carbon atom directly bonded to the –OH group.

Primary (1°) alcohols: The carbinol carbon is attached to one alkyl group (or none, in the case of methanol). Example: Ethanol, $CH_3CH_2OH$ .
Secondary (2°) alcohols: The carbinol carbon is attached to two alkyl groups. Example: Propan-2-ol, $CH_3CH(OH)CH_3$ .
Tertiary (3°) alcohols: The carbinol carbon is attached to three alkyl groups. Example: 2-methylpropan-2-ol, $(CH_3)_3COH$ .

Oxidation of Alcohols

Alcohols can be oxidised using a suitable oxidising agent, most commonly acidified potassium dichromate(VI), $K_2Cr_2O_7$ , in the presence of dilute sulfuric acid, $H_2SO_4$ . During this reaction, the orange dichromate(VI) ion, $Cr_2O_7^{2-}$ , is reduced to the green chromium(III) ion, $Cr^{3+}$ . This colour change provides a clear visual indication that oxidation has occurred. The product of the oxidation depends on the class of the alcohol and the reaction conditions.

General oxidation half-equation for the reagent: $Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^- \rightarrow 2Cr^{3+}(aq) + 7H_2O(l)$

Primary alcohols are oxidised first to aldehydes. If the aldehyde is not removed from the reaction mixture (e.g., by distillation), it will be further oxidised to a carboxylic acid. To obtain the carboxylic acid, the mixture is heated under reflux.
Secondary alcohols are oxidised to ketones. Ketones are resistant to further oxidation under these conditions, so reflux is typically used to ensure the reaction goes to completion.
Tertiary alcohols are resistant to oxidation. There is no hydrogen atom on the carbinol carbon to be removed, so no reaction occurs. The solution remains orange.

Esterification

Esterification is the reaction between an alcohol and a carboxylic acid to form an ester and water. This is a reversible condensation reaction, meaning it reaches an equilibrium. To favour the formation of the ester, the reaction is typically carried out by warming the reactants with a strong acid catalyst, such as concentrated sulfuric acid. Esters are known for their characteristic sweet, fruity smells and are used in food flavourings and perfumes.

$\text{Carboxylic Acid} + \text{Alcohol} \rightleftharpoons \text{Ester} + \text{Water} \\ \text{R-COOH} + \text{R'-OH} \xrightarrow{\text{conc. } H_2SO_4, \, \Delta} \text{R-COO-R'} + H_2O$

Dehydration of Alcohols

Dehydration is an elimination reaction where a molecule of water is removed from an alcohol to form an alkene. This reaction requires heating the alcohol with a concentrated acid catalyst, typically concentrated sulfuric acid ( $H_2SO_4$ ) at 170°C or by passing the alcohol vapour over a hot catalyst like aluminium oxide ( $Al_2O_3$ ) at around 350°C.

Alcohol \xrightarrow{conc. H_2SO_4, 170^\circ C} Alkene + Water

EXAM TIP

For unsymmetrical secondary or tertiary alcohols, dehydration can lead to more than one possible alkene product, depending on which adjacent carbon atom loses a hydrogen. You may be asked to draw all possible isomers.

Worked examples

See the formulas applied — reveal one step at a time, like the exam.

EXAMPLE 1

Butan-1-ol is heated under reflux with an excess of acidified potassium dichromate(VI). (i) State the class of butan-1-ol. (ii) Identify the organic product formed. (iii) Write a balanced equation for the reaction. Use [O] to represent the oxidising agent.

1
(i) Butan-1-ol is a primary alcohol because the carbon atom attached to the –OH group is bonded to only one other carbon atom.

EXAMPLE 2

Ethanol is warmed with propanoic acid in the presence of a few drops of concentrated sulfuric acid. (i) Name the ester formed. (ii) Draw the displayed formula of the ester.

1
(i) The name of the ester comes from the alcohol first, then the carboxylic acid. The alcohol 'ethanol' becomes 'ethyl'. The carboxylic acid 'propanoic acid' becomes 'propanoate'. So the ester is ethyl propanoate.

How it all connects

The big idea sits in the middle — tap a linked idea to explore the link.

MAIN IDEAAlcohols

Tap a linked idea to see how it connects back to the main topic — that connection is what examiners reward.

Glossary

Try to recall each definition before you reveal it.

Quick check

Answer in your head first — then tap to check. No pressure.

Revision flashcards

Flip the card. Test yourself before the exam.

QUESTION · 1 / 12

What is the functional group of an alcohol?

TAP OR SPACE TO FLIP

ANSWER

The hydroxyl group, –OH.

TAP OR SPACE TO FLIP BACK

1 / 12 · ← → space

Key takeaways

Review these before you close the topic — retrieval beats re-reading.

✓
Primary (1°) alcohols: The carbinol carbon is attached to one alkyl group (or none, in the case of methanol). Example: Ethanol, $CH_3CH_2OH$ .
✓
Secondary (2°) alcohols: The carbinol carbon is attached to two alkyl groups. Example: Propan-2-ol, $CH_3CH(OH)CH_3$ .
✓
Tertiary (3°) alcohols: The carbinol carbon is attached to three alkyl groups. Example: 2-methylpropan-2-ol, $(CH_3)_3COH$ .

Practice — then mark it

The whole point: a real Cambridge question, marked mark-by-mark.

Real past paper[0]

Practice Questions

Do it on paper → mark itMARKED MARK-BY-MARK · B1 / M1 / A1 · OFFICIAL SCHEME

Extra simulations & links

PhET, GeoGebra and other curated tools — open in a new tab.

Frequently asked

✓

Checkpoint

One marked question is worth ten re-reads — close the loop before you move on.

Checkpoint

Reading it isn’t knowing it — prove it.

Before you move on: do Practice Questions on paper, snap a photo, and get examiner-style feedback on exactly where you win and lose marks.

Attempt & get marked →Takes about a minute · you’ll land back on this lesson

← PREVIOUS15.1 Halogenoalkanes NEXT →17.1 Aldehydes and ketones

Alcohols

BY THE END, YOU CAN…

1Classify alcohols as primary, secondary, or tertiary based on their structure.
2Describe the oxidation of alcohols using acidified potassium dichromate(VI), predicting the products and stating the conditions for controlling the oxidation of primary alcohols.
3Explain the relative resistance to oxidation of primary, secondary, and tertiary alcohols.
4Describe the esterification of alcohols with carboxylic acids and the dehydration of alcohols to form alkenes, including reagents and conditions.

In simple terms

A friendly intro before the formal notes — no formulas yet.

Alcohols: The Reactive Hydroxyl

Alcohols are organic molecules containing a hydroxyl (–OH) group. Their classification as primary, secondary, or tertiary dictates how they react, particularly in oxidation reactions.

THINK OF IT LIKE…

1
Alcohols contain –OH; primary, secondary, tertiary classification.
2
Oxidation: primary → aldehyde → carboxylic acid; secondary → ketone.
3
Tertiary alcohols resist oxidation without C–C cleavage.
4
Esterification: alcohol + carboxylic acid ⇌ ester + water (acid catalyst).

Explore the concept

Use the live diagram and synced steps — play it or tap a step card to walk through.

Key formulas

Tap any symbol to reveal exactly what it means and its units.

$Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^- \rightarrow 2Cr^{3+}(aq) + 7H_2O(l)$

$\text{Carboxylic Acid} + \text{Alcohol} \rightleftharpoons \text{Ester} + \text{Water} \\ \text{R-COOH} + \text{R'-OH} \xrightarrow{\text{conc. } H_2SO_4, \, \Delta} \text{R-COO-R'} + H_2O$

Full topic notes

Formal explanation with the rigour you need for the exam.

Classification of Alcohols

Primary (1°) alcohols: The carbinol carbon is attached to one alkyl group (or none, in the case of methanol). Example: Ethanol, $CH_3CH_2OH$ .
Secondary (2°) alcohols: The carbinol carbon is attached to two alkyl groups. Example: Propan-2-ol, $CH_3CH(OH)CH_3$ .
Tertiary (3°) alcohols: The carbinol carbon is attached to three alkyl groups. Example: 2-methylpropan-2-ol, $(CH_3)_3COH$ .

Oxidation of Alcohols

General oxidation half-equation for the reagent: $Cr_2O_7^{2-}(aq) + 14H^+(aq) + 6e^- \rightarrow 2Cr^{3+}(aq) + 7H_2O(l)$

Primary alcohols are oxidised first to aldehydes. If the aldehyde is not removed from the reaction mixture (e.g., by distillation), it will be further oxidised to a carboxylic acid. To obtain the carboxylic acid, the mixture is heated under reflux.
Secondary alcohols are oxidised to ketones. Ketones are resistant to further oxidation under these conditions, so reflux is typically used to ensure the reaction goes to completion.
Tertiary alcohols are resistant to oxidation. There is no hydrogen atom on the carbinol carbon to be removed, so no reaction occurs. The solution remains orange.

Esterification

$\text{Carboxylic Acid} + \text{Alcohol} \rightleftharpoons \text{Ester} + \text{Water} \\ \text{R-COOH} + \text{R'-OH} \xrightarrow{\text{conc. } H_2SO_4, \, \Delta} \text{R-COO-R'} + H_2O$

Dehydration of Alcohols

Alcohol \xrightarrow{conc. H_2SO_4, 170^\circ C} Alkene + Water

EXAM TIP

Worked examples

See the formulas applied — reveal one step at a time, like the exam.

EXAMPLE 1

1
(i) Butan-1-ol is a primary alcohol because the carbon atom attached to the –OH group is bonded to only one other carbon atom.

EXAMPLE 2

Ethanol is warmed with propanoic acid in the presence of a few drops of concentrated sulfuric acid. (i) Name the ester formed. (ii) Draw the displayed formula of the ester.

1
(i) The name of the ester comes from the alcohol first, then the carboxylic acid. The alcohol 'ethanol' becomes 'ethyl'. The carboxylic acid 'propanoic acid' becomes 'propanoate'. So the ester is ethyl propanoate.

How it all connects

The big idea sits in the middle — tap a linked idea to explore the link.

MAIN IDEAAlcohols

Tap a linked idea to see how it connects back to the main topic — that connection is what examiners reward.

Glossary

Try to recall each definition before you reveal it.

Quick check

Answer in your head first — then tap to check. No pressure.

Revision flashcards

Flip the card. Test yourself before the exam.

QUESTION · 1 / 12

What is the functional group of an alcohol?

TAP OR SPACE TO FLIP

ANSWER

The hydroxyl group, –OH.

TAP OR SPACE TO FLIP BACK

1 / 12 · ← → space

Key takeaways

Review these before you close the topic — retrieval beats re-reading.

✓
Primary (1°) alcohols: The carbinol carbon is attached to one alkyl group (or none, in the case of methanol). Example: Ethanol, $CH_3CH_2OH$ .
✓
Secondary (2°) alcohols: The carbinol carbon is attached to two alkyl groups. Example: Propan-2-ol, $CH_3CH(OH)CH_3$ .
✓
Tertiary (3°) alcohols: The carbinol carbon is attached to three alkyl groups. Example: 2-methylpropan-2-ol, $(CH_3)_3COH$ .

Practice — then mark it

The whole point: a real Cambridge question, marked mark-by-mark.

Real past paper[0]

Practice Questions

Do it on paper → mark itMARKED MARK-BY-MARK · B1 / M1 / A1 · OFFICIAL SCHEME

Extra simulations & links

PhET, GeoGebra and other curated tools — open in a new tab.

Frequently asked

✓

Checkpoint

One marked question is worth ten re-reads — close the loop before you move on.

Checkpoint

Reading it isn’t knowing it — prove it.

Before you move on: do Practice Questions on paper, snap a photo, and get examiner-style feedback on exactly where you win and lose marks.

Attempt & get marked →Takes about a minute · you’ll land back on this lesson

← PREVIOUS15.1 Halogenoalkanes NEXT →17.1 Aldehydes and ketones

Revise Alcohols for Cambridge 9701 (16.1)

In simple terms

Explore the concept

Key formulas

Full topic notes

Classification of Alcohols

Oxidation of Alcohols

Esterification

Dehydration of Alcohols

Worked examples

How it all connects

Glossary

Quick check

Revision flashcards

Key takeaways

Practice — then mark it

Practice Questions

Extra simulations & links

Frequently asked

Checkpoint

Reading it isn’t knowing it — prove it.

In simple terms

Explore the concept

Key formulas

Full topic notes

Classification of Alcohols

Oxidation of Alcohols

Esterification

Dehydration of Alcohols

Worked examples

How it all connects

Glossary

Quick check

Revision flashcards

Key takeaways

Practice — then mark it

Practice Questions

Extra simulations & links

Frequently asked

Checkpoint

Reading it isn’t knowing it — prove it.

Discuss Alcohols