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Leaving Cert Physics & Chemistry: Carboxylic acids & esters

How often Carboxylic acids & esters comes up on the Physics & Chemistry papers, every year it was asked, and questions to try.

HL Asked on 7 of the last 9 Higher Level papers, most recently in 2025. most years

OL Asked on 6 of the last 9 Ordinary Level papers, most recently in 2025. most years

Carboxylic acids & esters, Higher Level(7 marks)

Quick ones on Carboxylic acids & esters.

(a)Functional group of ethanoic acid?
  1. Hydroxyl, –OH, on its own
  2. Carboxyl, –COOH
  3. Aldehyde, –CHO
(b)Propanoic acid reacts with ethanol (concentrated H2SO4 catalyst). Which ester forms?
  1. Ethyl ethanoate
  2. Propyl ethanoate
  3. Ethyl propanoate
(c)Ethanoic acid is added to sodium carbonate. Which gas fizzes off?
  1. Carbon dioxide
  2. Oxygen
  3. Hydrogen
Show the answers

(a) Carboxyl, –COOH

(b) Ethyl propanoate

(c) Carbon dioxide

Your turn: Higher Level questions on Carboxylic acids & esters.

Higher Level

Asked on 7 of the last 9 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q11
2024Q7(q)
2023Q11
2022Q7(q), Q11
2021Not asked
2019Q7(o)
2018Not asked
2017Q11
2016Q11

Links open the State Examinations Commission’s paper for that year.

More Carboxylic acids & esters questions

Carboxylic acids & esters, 2 marks

The acid in vinegar is…

  1. Citric acid
  2. Methanoic acid
  3. Ethanoic acid
Show the answer

Ethanoic acid

Vinegar is a dilute solution of ethanoic acid, CH3COOH. Citric acid is found in lemons and oranges.

Ordinary Level

Asked on 6 of the last 9 Ordinary Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q7(p)
2024Q7(r)
2023Not asked
2022Q7(r)
2021Not asked
2019Q7(n)
2018Not asked
2017Q7(g)
2016Q7(o)

Links open the State Examinations Commission’s paper for that year.

More Carboxylic acids & esters questions

Carboxylic acids & esters, 2 marks

The functional group of a carboxylic acid is?

  1. Hydroxyl (-OH)
  2. Carbonyl (C=O)
  3. Carboxyl (-COOH)
Show the answer

Carboxyl (-COOH)

Carboxylic acids such as ethanoic acid, CH3COOH, are weak acids. The -COOH group gives up its H as a proton.

Carboxylic acids & esters, 2 marks

Vinegar is a dilute solution of which acid?

  1. Hydrochloric acid
  2. Ethanoic acid
  3. Methanoic acid
Show the answer

Ethanoic acid

Vinegar is about 5% ethanoic acid (acetic acid). It is a weak acid, so it is safe to put on chips.

Carboxylic acids & esters, 2 marks

An ester is formed when a carboxylic acid reacts with?

  1. An alcohol
  2. An alkane
  3. A metal
Show the answer

An alcohol

Acid + alcohol → ester + water. Esters have sweet, fruity smells and are used in flavourings and perfumes.

Other Physics & Chemistry topics

All of Leaving Cert Physics & Chemistry