AQA GCSE Chemistry (8462), Higher tier · Organic chemistry › Reactions of alkenes and alcohols
Practise Carboxylic acids. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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What is the functional group of the carboxylic acids?
–COOH
A student added ethanoic acid to sodium carbonate. Give one observation.
Fizzing (bubbles).
Name the carboxylic acid HCOOH.
Methanoic acid
Suggest the name of the ester formed from methanol and propanoic acid.
Methyl propanoate
Ethanoic acid reacts with ethanol, in the presence of an acid catalyst, to form an ester and water. CH3COOH + C2H5OH → CH3COOC2H5 + H2O Relative formula masses (Mr): CH3COOH = 60 C2H5OH = 46 CH3COOC2H5 = 88 Name the ester formed.
Ethyl ethanoate
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) What is the functional group of the carboxylic acids?[1]
(b) Name the carboxylic acid with the formula CH3COOH.[1]
(c) Name the gas produced when a carboxylic acid reacts with a carbonate.[1]
(d) Name the ester produced when ethanol reacts with ethanoic acid.[1]
Show the answer and mark scheme
(a)Answer: –COOH
–COOH
(b)Answer: Ethanoic acid
ethanoic acid
(c)Answer: Carbon dioxide
carbon dioxide
(d)Answer: Ethyl ethanoate
ethyl ethanoate
Question 2Medium6 marks
Ethanoic acid is a carboxylic acid.
(a) A student added ethanoic acid to sodium carbonate. Give one observation.[1]
(b) Name the salt formed in this reaction.[1]
(c) Describe a test for the gas produced and give the result.[2]
(d) Ethanoic acid reacts with ethanol to produce an ester. Name the catalyst used and the other product of the reaction.[2]
Show the answer and mark scheme
(a)Answer: Fizzing (bubbles).
fizzing / bubbles / the solid disappears
(b)Answer: Sodium ethanoate
sodium ethanoate
(c)Answer: Bubble the gas through limewater: it turns milky.
bubble the gas through limewater
the limewater turns milky / cloudy
(d)Answer: An acid catalyst (concentrated sulfuric acid); water.
(concentrated) sulfuric acid / an acid catalyst
water
Question 3Hard8 marks
A student measured the pH of two acids. Both acids had a concentration of 0.10 mol/dm3.
Hydrochloric acid: pH 1
Ethanoic acid: pH 3
(a) Explain why ethanoic acid has a higher pH than hydrochloric acid of the same concentration.[3]
(b) Write an equation to show how ethanoic acid ionises in water.[2]
(c) How many times greater is the concentration of hydrogen ions in the hydrochloric acid than in the ethanoic acid?[1]
(d) The student added the same mass of magnesium ribbon to each acid. Predict and explain the difference in the rate of reaction.[2]
Show the answer and mark scheme
(a)Answer: Ethanoic acid is a weak acid: it only partially ionises in water, so the concentration of H+ ions is lower.
ethanoic acid is a weak acid
it only partially ionises in water
so the concentration of H+ ions is lower
(b)Answer: CH3COOH ⇌ CH3COO− + H+
correct species: CH3COOH → CH3COO− + H+
reversible arrow (⇌) used
(c)Answer: 100 times
100
(d)Answer: The ethanoic acid reacts more slowly, because the lower H+ concentration gives fewer collisions per second.
the reaction with ethanoic acid is slower
because the concentration of H+ ions is lower, so there are fewer collisions per second