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Leaving Cert Chemistry: Organic reactions

How often Organic reactions comes up on the Chemistry papers, every year it was asked, and questions to try.

HL Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

OL Asked on 10 of the last 10 Ordinary Level papers, most recently in 2026. banker

June 2027 is the first exam on the new Chemistry course. These come from the 2016–2026 papers, so read them as a guide.

Organic reactions, Higher Level(8 marks)

Quick ones on Organic reactions.

(a)Product of the oxidation of a secondary alcohol?
  1. An aldehyde
  2. A ketone
  3. A carboxylic acid
(b)Catalyst used to add hydrogen across a carbon to carbon double bond?
  1. Vanadium(V) oxide
  2. Manganese dioxide
  3. Nickel
(c)Name of the reaction between an alcohol and a carboxylic acid to form an ester and water?
  1. Esterification
  2. Polymerisation
  3. Saponification
Show the answers

(a) A ketone

(b) Nickel

(c) Esterification

Your turn: Higher Level questions on Organic reactions.

Higher Level

Asked on 10 of the last 10 Higher Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q4(k), Q8, Q11(a)
2025Q8, Q10(b)
2024Q8
2023Q8
2022Q8, Q11(b)
2021Q8
2019Q8, Q10(a)
2018Q4(h)
2017Q8, Q10(c)
2016Q8

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

More Organic reactions questions

Organic reactions, 2 marks

In the free radical chlorination of methane, which step can produce some ethane?

  1. Initiation
  2. Propagation
  3. Termination
Show the answer

Termination

Two methyl radicals join: CH3. + CH3. -> C2H6. Finding ethane in the products is evidence for the free radical mechanism.

Organic reactions, 2 marks

Reagent used on the course to reduce an aldehyde or ketone to an alcohol?

  1. Acidified potassium manganate(VII)
  2. Hydrogen with a nickel catalyst
  3. Fehling's solution
Show the answer

Hydrogen with a nickel catalyst

Hydrogen adds across the C=O. Fehling's solution and potassium manganate(VII) are oxidising agents.

Organic reactions, 2 marks

Poly(ethene) lasts for centuries in the environment because?

  1. Its strong, non-polar C-C and C-H bonds are not attacked by micro-organisms
  2. It dissolves slowly in rain, so it takes centuries to disappear
  3. It is an ionic compound whose lattice cannot be broken down
Show the answer

Its strong, non-polar C-C and C-H bonds are not attacked by micro-organisms

Addition polymers are chemically stable, like long alkanes. They build up in landfill and break into microplastics.

Ordinary Level

Asked on 10 of the last 10 Ordinary Level papers, most recently in 2026. banker

Every paper, year by year

YearWhere it came up
2026Q8
2025Q8
2024Q8
2023Q8
2022Q8
2021Q8
2019Q8
2018Q8
2017Q4(g), Q8
2016Q8

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

More Organic reactions questions

Organic reactions, 2 marks

Product formed when bromine adds to ethene?

  1. Bromoethene
  2. Bromomethane
  3. 1,2-dibromoethane
Show the answer

1,2-dibromoethane

One bromine atom adds to each carbon of the double bond. This is why bromine water is decolourised.

Organic reactions, 2 marks

Product of the addition of hydrogen chloride to ethene?

  1. Ethanol
  2. Chloroethane
  3. Chloroethene
Show the answer

Chloroethane

HCl adds across the double bond: CH2=CH2 + HCl gives CH3CH2Cl. The product is saturated.

Organic reactions, 2 marks

Product when ethanol is fully oxidised?

  1. Ethanoic acid
  2. Ethene
  3. Ethane
Show the answer

Ethanoic acid

Ethanol is oxidised first to ethanal and then to ethanoic acid. Wine left open turns sour in this way.

Other Chemistry topics

All of Leaving Cert Chemistry