ChemistryICSE Class 10 · Organic Chemistry

Ethanol: Preparation, Properties and Uses (ICSE Class 10)

Updated 17 October 2026 · Fact-checked

Ethanol, C₂H₅OH, is the second member of the alcohol series. It is prepared by hydrolysis of an alkyl halide such as bromoethane with aqueous alkali. It is a colourless liquid, miscible with water, which burns with a blue flame, reacts with sodium to release hydrogen, forms the ester ethyl ethanoate with acetic acid, and is dehydrated by concentrated sulphuric acid to ethene. Denatured spirit is ethanol made unfit for drinking; spurious alcohol is harmful.

Understand Ethanol: Preparation, Properties and Uses

1. Structure. Ethanol, $C_{2} H_{5} O H$ or $C H_{3} C H_{2} O H$ , contains the alcohol group -OH attached to an ethyl group. It is the member of the homologous series of alcohols with two carbon atoms (general formula $C_{n} H_{2 n + 1} O H$ ).

2. Preparation by hydrolysis of an alkyl halide. Heating bromoethane with aqueous sodium hydroxide (or potassium hydroxide) replaces the halogen by -OH:
$C_{2} H_{5} B r + N a O H (a q) \to C_{2} H_{5} O H + N a B r$
The aqueous alkali is essential; with alcoholic KOH, ethene forms instead (see the ethene page).

3. Physical properties.

Colourless liquid with a characteristic smell and a burning taste.
Soluble in water in all proportions (miscible).
Less dense than water; it has a low boiling point.
It is a non-electrolyte: neutral to litmus and does not give ions in water.

4. Chemical properties.

Combustion: burns in air with a pale blue, almost non-luminous flame, giving carbon dioxide and water: $C_{2} H_{5} O H + 3 O_{2} \to 2 C O_{2} + 3 H_{2} O$ .
With sodium: brisk effervescence of hydrogen, forming sodium ethoxide: $2 C_{2} H_{5} O H + 2 N a \to 2 C_{2} H_{5} O N a + H_{2}$ .
Esterification: with acetic acid, in the presence of concentrated sulphuric acid and heat, it forms the ester ethyl ethanoate (fruity smell) and water: $C H_{3} C O O H + C_{2} H_{5} O H ⇌ C H_{3} C O O C_{2} H_{5} + H_{2} O$ .
Dehydration: with excess concentrated sulphuric acid at about 170 °C (a standard textbook condition), it loses water to form ethene: $C_{2} H_{5} O H co n c . H_{2} S O_{4} C_{2} H_{4} + H_{2} O$ . At a lower temperature with excess ethanol, ether forms, but only ethene is asked for the syllabus.

5. Denatured spirit and spurious alcohol.

Denatured (methylated) spirit is ethanol to which methanol, a poisonous substance, and a coloured or foul-tasting substance are added so that it cannot be drunk. The ethanol is then sold cheaply, without a tax, for industrial use.
Spurious alcohol is an adulterated product that may contain methanol; drinking it can cause blindness or death.

6. Uses. As a solvent for paints, varnishes, perfumes and medicines; in tinctures and cough syrups; as an antiseptic; as a fuel and fuel additive; and to prepare ethanoic acid, ethene and esters.

Ethanol: Preparation, Properties and Uses: formulas and key facts

Hydrolysis of bromoethane: $C_{2} H_{5} B r + N a O H (a q) \to C_{2} H_{5} O H + N a B r$
Combustion: $C_{2} H_{5} O H + 3 O_{2} \to 2 C O_{2} + 3 H_{2} O$
With sodium: $2 C_{2} H_{5} O H + 2 N a \to 2 C_{2} H_{5} O N a + H_{2}$
Esterification: $C H_{3} C O O H + C_{2} H_{5} O H ⇌ C H_{3} C O O C_{2} H_{5} + H_{2} O$
Dehydration: $C_{2} H_{5} O H co n c . H_{2} S O_{4} C_{2} H_{4} + H_{2} O$

How to solve Ethanol: Preparation, Properties and Uses questions

For ethanol equations, identify the reagent and then write the product.

1Aqueous alkali and bromoethane means hydrolysis, giving ethanol.
2Sodium means hydrogen is released and sodium ethoxide forms (2 : 2 : 2 : 1).
3Oxygen means complete combustion to CO₂ and H₂O.
4Carboxylic acid with conc. H₂SO₄ means an ester plus water (esterification, reversible).
5Excess conc. H₂SO₄ with heat means dehydration to ethene.
6For numericals, convert grams to moles (M of ethanol = 46 g/mol), apply the ratio and use 22.4 dm³ per mole for gases.

Ethanol: Preparation, Properties and Uses in real life

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Why a hand-sanitiser catches fire near a flame

Suppose a hand sanitiser contains a high percentage of ethanol, and a student notices a pale blue flame when a drop meets a spark.

Write the equation for what burns and name the products.

Try it first, then show the solutionSolution

Ethanol burns in oxygen: $C_{2} H_{5} O H + 3 O_{2} \to 2 C O_{2} + 3 H_{2} O$ .
The products are carbon dioxide and water; the flame is pale blue and almost non-luminous.

Answer: Ethanol burns to carbon dioxide and water with a pale blue flame.

Memory hook: Alcohol burns blue.

Tricks to remember Ethanol: Preparation, Properties and Uses

Short memory aids. Say each one aloud once, then use it on a question the same day.

Bromoethane + aqueous alkali = ethanol
Aqueous gives alcohol (hydrolysis); alcoholic gives ethene.
Use it when: Choosing between the two reactions of alkyl halides.
2-2-2-1
In the sodium reaction: 2 ethanol, 2 sodium, 2 ethoxide, 1 hydrogen.
Use it when: Balancing and mole calculations.
Conc. acid: Dehydrate; Dilute-ish: Dissolve
Concentrated sulphuric acid takes water away from ethanol (ethene); it also catalyses the ester formation.
Use it when: Two uses of the acid.

Ethanol: Preparation, Properties and Uses: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

Example 1: Name the product · 2 marks · Short answerBoard level

Name the organic product when ethanol reacts with (a) sodium, (b) excess concentrated sulphuric acid at the required temperature.

Try it first, then show the solutionSolution

(a) Sodium ethoxide (with hydrogen).
(b) Ethene (by dehydration).

Answer: (a) Sodium ethoxide (b) Ethene.

Example 2: Equation for preparation · 2 marks · Short answerBoard level

Write the equation for preparing ethanol from bromoethane. Name the type of reaction and the reagent used.

Try it first, then show the solutionSolution

$C_{2} H_{5} B r + N a O H (a q) \to C_{2} H_{5} O H + N a B r$ .
The reaction is hydrolysis and the reagent is aqueous sodium (or potassium) hydroxide.

Answer: Hydrolysis; aqueous NaOH or KOH.

Example 3: Hydrogen from sodium · 3 marks · Short answerHarder board level

Calculate the volume of hydrogen at S.T.P. liberated when 4.6 g of ethanol reacts with excess sodium, and the mass of sodium ethoxide formed. (C = 12, H = 1, O = 16, Na = 23)

Try it first, then show the solutionSolution

Molar mass of C₂H₅OH = 24 + 6 + 16 = 46 g/mol; moles = 4.6 / 46 = 0.1.
2C2H5OH gives 1 H₂, so H₂ = 0.05 mol = 0.05 x 22.4 = 1.12 dm³.
C₂H₅ONa: M = 68 g/mol; 0.1 mol = 6.8 g.

Answer: 1.12 dm³ of hydrogen; 6.8 g of sodium ethoxide.

Example 4: Combustion numerical · 3 marks · Short answerHarder board level

Calculate the volume of carbon dioxide at S.T.P. and the mass of water formed on complete combustion of 23 g of ethanol. (C = 12, H = 1, O = 16)

Try it first, then show the solutionSolution

$C_{2} H_{5} O H + 3 O_{2} \to 2 C O_{2} + 3 H_{2} O$ ; moles of ethanol = 23 / 46 = 0.5.
CO₂ = 2 x 0.5 = 1.0 mol = 22.4 dm³.
H₂O = 3 x 0.5 = 1.5 mol = 1.5 x 18 = 27 g.

Answer: 22.4 dm³ of CO₂ and 27 g of water.

Example 5: Ester and the role of acid · 5 marks · Long answerHOTS / competency

Ethanol is heated with ethanoic acid and a few drops of concentrated sulphuric acid. (a) Write the equation and name the ester. (b) What is this reaction called? (c) Give the role of sulphuric acid. (d) If 6.0 g of acetic acid (M = 60) could be completely converted, what mass of ester (M = 88) would form?

Try it first, then show the solutionSolution

(a) $C H_{3} C O O H + C_{2} H_{5} O H ⇌ C H_{3} C O O C_{2} H_{5} + H_{2} O$ ; ethyl ethanoate.
(b) Esterification.
(c) It acts as a catalyst and a dehydrating agent, which helps the reaction.
(d) Moles of acid = 6.0 / 60 = 0.1; ester = 0.1 x 88 = 8.8 g (assuming complete conversion).

Answer: (a) Ethyl ethanoate (b) Esterification (c) Catalyst and dehydrating agent (d) 8.8 g.

Where students lose marks in Ethanol: Preparation, Properties and Uses

The slips examiners see most often, and what to write instead.

Mistake: Using alcoholic KOH for ethanol
Alcoholic KOH removes HBr to form ethene; aqueous alkali substitutes the halogen.
Do this: Write aqueous NaOH or KOH.
Usually costs: 1 mark.
Mistake: Forgetting H₂SO₄ catalyst in esterification
Concentrated sulphuric acid and heat are required.
Do this: Mention catalyst and heat.
Usually costs: 1 mark.
Mistake: Writing C₂H₅ONa without H₂
The gas evolved is omitted or the equation is not balanced.
Do this: Balance as 2 : 2 : 2 : 1.
Usually costs: 1 mark.
Mistake: Confusing denatured spirit with spurious alcohol
Both contain methanol, but denatured spirit is made deliberately unfit to drink, while spurious alcohol is illegally adulterated.
Do this: State the purpose of each.
Usually costs: 1 mark.

Exam tips

Give the name and formula of the organic product in every equation.
For dehydration, mention "excess concentrated sulphuric acid" and heat.
For esterification, name the ester and the smell (fruity).
Practice mole numericals with M = 46 g/mol for ethanol.

Practice questions on Ethanol: Preparation, Properties and Uses

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
Ethanol is prepared by the hydrolysis of bromoethane with:
(a) alcoholic KOH
(b) aqueous NaOH
(c) concentrated H₂SO₄
(d) dry HCl
Hint
Aqueous alkali.
Answer
(b) aqueous NaOH.
Q2 · 1 mark · MCQBoard level
Ethanol is NOT:
(a) soluble in water
(b) an electrolyte
(c) a liquid at room temperature
(d) combustible
Hint
Does it give ions?
Answer
(b) an electrolyte.
Q3 · 2 marks · Short answerBoard level
State what is observed when a small piece of sodium is dropped into ethanol. Write the equation.
Hint
A gas is evolved.
Answer
Brisk effervescence of hydrogen and sodium dissolves slowly; $2 C_{2} H_{5} O H + 2 N a \to 2 C_{2} H_{5} O N a + H_{2}$ .
Q4 · 3 marks · Short answerHarder board level
State two industrial uses of ethanol. Explain why methylated spirit must never be drunk, and say what makes spurious alcohol dangerous.
Hint
Methanol is poisonous.
Answer
Uses: a solvent for paints and varnishes; making ethanoic acid and esters. Methylated spirit has poisonous methanol and other additives added on purpose to make it unfit to drink. Spurious alcohol is adulterated, may contain methanol, and can cause blindness or death.
Q5 · 3 marks · Short answerHarder board level
Calculate the volume of ethene at S.T.P. obtained from 9.2 g of ethanol on dehydration with concentrated sulphuric acid (assume complete reaction). (C = 12, H = 1, O = 16)
Hint
1 mol ethanol gives 1 mol ethene.
Answer
Moles of ethanol = 9.2 / 46 = 0.2; ethene = 0.2 mol = 0.2 x 22.4 = 4.48 dm³.
Q6 · 1 mark · Assertion-reasonHarder board level
Assertion (A): Ethanol reacts with sodium but does not turn litmus red or blue.
Reason (R): Ethanol is neutral and releases hydrogen from its -OH group in the reaction with sodium.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.
Hint
Both parts concern the -OH group.
Answer
(b).
Q7 · 5 marks · Long answerHarder board level
Compound X (C₂H₆O) reacts with sodium to give hydrogen. With acetic acid and concentrated sulphuric acid it gives a fruity-smelling liquid Y. When heated with excess concentrated sulphuric acid, it gives a hydrocarbon Z. Identify X, Y and Z and write the three equations.
Hint
X is an alcohol.
Answer
X: ethanol; Y: ethyl ethanoate; Z: ethene. $2 C_{2} H_{5} O H + 2 N a \to 2 C_{2} H_{5} O N a + H_{2}$ ; $C H_{3} C O O H + C_{2} H_{5} O H ⇌ C H_{3} C O O C_{2} H_{5} + H_{2} O$ ; $C_{2} H_{5} O H co n c . H_{2} S O_{4} C_{2} H_{4} + H_{2} O$ .
Q8 · 3 marks · Short answerHOTS / competency
A student adds sodium hydroxide to bromoethane and boils: (i) in water; (ii) in alcohol. (a) Name the main organic product in (i). (b) Name the main product in (ii). (c) What is the practical significance of the solvent?
Hint
Substitution versus elimination.
Answer
(a) Ethanol. (b) Ethene. (c) The solvent decides substitution (hydrolysis) in aqueous alkali or elimination (dehydrohalogenation) in alcoholic alkali.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.Formula of ethanol?Show answer
C₂H₅OH.
2.Gas evolved when ethanol reacts with sodium?Show answer
Hydrogen.
3.Product of ethanol with excess conc. H₂SO₄ (heat)?Show answer
Ethene.
4.Name of the ester from ethanol and acetic acid?Show answer
Ethyl ethanoate.
5.Why is methanol added to ethanol?Show answer
To make it unfit for drinking (denaturing).

Ethanol: Preparation, Properties and Uses: frequently asked questions

How is ethanol prepared in the syllabus?

By hydrolysis of an alkyl halide such as bromoethane with aqueous alkali.

Is ethanol acidic?

No, it is neutral to litmus, although it reacts with sodium.

What is the flame colour when ethanol burns?

Pale blue.

What is spurious alcohol?

Adulterated alcohol, possibly containing methanol, harmful or fatal to drink.