AQA GCSE Chemistry Foundation (8462), Foundation tier · Organic chemistry › Reactions of alkenes and alcohols
Practise Alcohols. 8 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
The alcohols: the –OH functional group, the first four alcohols, their reactions with sodium, air, water and oxidising agents, their uses, and making ethanol by fermentation. GCSE Chemistry only. Expect naming, observations, combustion equations, fermentation conditions and evaluate questions based on data.
The product is a dilute solution of ethanol, which can be concentrated by fractional distillation.
How to answer each type of question
Describe what you would see
2 to 4 marksGrade 5
Give observations, not just product names: fizzing, bubbles, the sodium getting smaller.
Name any gas produced: hydrogen with sodium.
With water, say that the alcohol dissolves and that the solution is neutral.
Example. A student tests ethanol in two ways. (a) Ethanol is added to water containing universal indicator. What colour is the indicator? Give a reason. (b) A small piece of sodium is added to ethanol. Describe two things the student would see.
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(a) Green (1), because ethanol forms a neutral solution, pH 7 (1). (b) Fizzing or bubbles of gas (1). The sodium gets smaller and disappears (1).
Don’t lose marks
Calling ethanol a hydrocarbon. It contains oxygen.
Saying alcohols form acidic or alkaline solutions. Their solutions are neutral (pH 7).
Saying sodium and an alcohol give oxygen or carbon dioxide. The gas is hydrogen.
Forgetting the H in the –OH when counting hydrogen atoms for a combustion equation.
Saying fermentation needs a high temperature. It needs a warm temperature; too hot denatures the enzymes.
More tips
Memory tricks
'-ol' means alcohol: methanol, ethanol, propanol, butanol.
Counting hydrogens: C2H5OH has 5 + 1 = 6 H atoms, which make 3H2O.
Alcohol combustion: an alcohol with n carbon atoms needs 1.5n molecules of O2. Ethanol needs 3; butanol needs 6.
Oxidising an alcohol gives the acid with the same number of carbons: ethanol → ethanoic acid, propanol → propanoic acid.
Fermentation needs a warm, airless, sugary home for the yeast.
Exam technique
In 'describe what you would see' questions, give observations (fizzing, the sodium disappears), not just 'hydrogen is made'.
Balanced equations are only expected for alcohol combustion. For other reactions, word equations and names are enough.
In evaluate questions, give points for and against each method and finish with a conclusion that follows from them.
Give the fermentation temperature as a number (about 30 °C) as well as the word 'warm'.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name the functional group of the alcoholsThe –OH group.
Grade 3
Give the main uses of alcoholsAs fuels and solvents; ethanol is the main alcohol in alcoholic drinks.
Grade 4
Name and draw the first four alcoholsMethanol, ethanol, propanol and butanol; ethanol is CH3CH2OH.
Grade 4
State the conditions for fermentationSugar solution, yeast, a warm temperature (about 30 °C) and no air.
Grade 5
Describe the reactions of alcoholsSodium: fizzing (hydrogen). Water: dissolves, neutral solution. Oxidising agent: a carboxylic acid forms.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
What is the functional group of the alcohols?
–OH
The student added a small piece of sodium to propanol. Give one observation and name the gas produced.
Bubbles (fizzing); hydrogen.
Give the molecular formula of ethanol.
C2H6O
A student added a small piece of sodium to ethanol in a test tube. Describe one observation the student would make.
Bubbles (fizzing) are seen; the sodium may move around and get smaller.
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
(a) What is the functional group of the alcohols?[1]
(b) Name the alcohol with the formula CH3OH.[1]
(c) Which two of these are main uses of alcohols? Tick (✓) two boxes.[2]
Fuels
Solvents
Fertilisers
Food colourings
Extracting metals
(d) Ethanol is produced when sugar solutions are fermented. What is added to the sugar solution to ferment it?[1]
Show the answer and mark scheme
(a)Answer: –OH
–OH
(b)Answer: Methanol
methanol
(c)Answer: Fuels; Solvents
(d)Answer: Yeast
yeast
Question 2Medium7 marks
A student carried out some reactions with propanol, C3H7OH.
(a) The student added a small piece of sodium to propanol. Give one observation and name the gas produced.[2]
(b) The student added propanol to water containing universal indicator. What would the student see? Give the pH of the solution.[2]
(c) The student warmed propanol with an oxidising agent. Name the organic product.[1]
(d) Write a balanced equation for the complete combustion of propanol.[2]
Show the answer and mark scheme
(a)Answer: Bubbles (fizzing); hydrogen.
bubbles / fizzing / the sodium gets smaller
hydrogen
(b)Answer: The propanol mixes with the water; the indicator stays green (pH 7).