Updated January 2026

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Table of contents

Predictions 2026

General patterns of LC Chemistry questions

Deferred papers and their impact on the main sitting of the Leaving Cert Chemistry exam

Track record

2025, 2024, 2023, 2022, 2021, 2020, 2019

Predictions 2026

Section 1: Experiments 

Experiment predictions are based on two things: 

• The last time they appeared on the paper. 
• How often they appear on the paper (we will go back as far as 2006 for this analysis). Experiment likelihood is ranked below based on these two metrics. 

Experiment 1: Titration 

• Iodine-thiosulfate titration. 

○ Last seen: 2015. 

○ Has come up: 2 times. 

• Dissolved oxygen. 

○ Last seen: 2019. 

○ Has come up: 2 times. 

• Water crystals. 

○ Last seen: 2020. 

○ Has come up: 3 times. 

• Hypochlorite in Bleach. 

○ Last seen: 2021. 

○ Has come up: 2 times. 

• Potassium Manganate (VII) and Ammonium Iron (II) Sulfate. 

○ Last seen: 2023. 

○ Has come up: 2 times. 

• Total Hardness with EDTA. 

○ Last seen: 2022. 

○ Has come up: 3 times. 

• HCl versus Na2CO3. 

○ Last seen: 2012. 

○ Has come up: 1 time. 

○ Not as detailed as the others, so unlikely. 

• Ethanoic Acid in Vinegar. 

○ Last seen: 2024. 

○ Has come up: 3 times. 

• Iron in Iron Tablets. 

○ Last seen: 2025. 

○ Has come up: 2 times.

Experiment 2: Organic Chemistry (This often mixes multiple experiments from the list below) 

• Recrystallisation of Benzoic Acid 

○ Last seen: 2024 

○ Has come up: 8 time 

○ At least some part of this experiment has been coming up every second year since 2011, so it’s particularly worth learning, especially the melting point part, as it has not been seen for the longest 

• Synthesis of Benzoic Acid from Phenylmethanol 

○ Last seen: 2020 

○ Has come up: 2 times 

• Ethene/Ethyne. 

○ Last seen: 2023 

○ Has come up: 6 times 

○ Ethene is more likely than Ethyne 

The rest below are less likely, but you should still learn them if you’re planning on definitely answering Q2, since Q2 often mixes multiple experiments: 

• Ethanal/Ethanol/Ethanoic Acid Reactions 

○ Last seen: 2024 

○ Has come up: 5 times 

○ Is often a smaller part mixed in with another question, and comes up in Q8 ● Preparation of Soap 

○ Last seen: 2024 

○ Has come up: 7 times 

• Chromatography 

○ Last seen: 2008 

○ Has come up: 1 time 

○ Has a good chance of coming up in Q4 or Q10/11 if not here 

• Clove Oil 

○ Last seen: 2025 

○ Has come up: 4 times 

Experiment 3: Other Experiments 

• Suspended/Dissolved solids + pH of water // Concentration of free chlorine ○ These two experiments were mixed together in 2015 and have not been seen since then
• Measurement of the molecular mass of a volatile liquid 

○ Last seen: 2019 

○ Has come up: 2 times 

• Flame tests/Anion tests are worth learning, as they could also come up in Section 2 (usually Q4, Q5, or Q10/11) 

○ Last seen in Q3 in 2021 

• Rates of reaction experiments came up in both 2025 and 2024, so they are very unlikely for 2026 
• Heat of reaction experiment came up in 2025 as a theory question, and in 2023 as an experiment, so it is also unlikely for 2026. 

Section 2: Theory 

The theory section tends to be much less predictable, but below are some things that tend to come up every year and some things that have not appeared on the paper in a while. 

Question 4:

Short questions based on various topics 

Question 5 

• Periodic table (e.g. Mendeleev) and trends in the Periodic Table 
• Writing s,p,d configurations 
• Atomic structure – Thomson, Rutherford 
• Bonding 
• Bohr’s atomic theory 
• Definitions – electronegativity, energy level, ionisation energy 

Question 6: Fuels and heats of reaction 

• Thermochemistry calculations – almost guaranteed* 
• IUPAC naming – almost guaranteed* 
• Identifying/comparing structural isomers 
• Ways of increasing octane numbers 
• Drawing hydrocarbons 
• Definitions – e.g. Hess’ law, heat of formation 

Question 8: Organic chemistry 

• IUPAC naming and drawing molecules – almost guaranteed* 
• Geometry of molecules
• Recognising different types of organic reactions (addition, substitution etc.) ● Properties of different families of compounds and comparing them to each other e.g. esters, alcohols, boiling points, solubility in water, etc. 
• A mechanism is less likely to appear this year 

Questions 7,9 

One of Q7 or Q9 is almost always chemical equilibrium. The other question is almost always acids & bases, but is sometimes rates of reaction. 

Rates of Reaction could be particularly likely for 2026, since it hasn’t been in section B since 2023, the longest gap without rates of reaction appearing in section B ever. Water could be mixed in with either Q7 or Q9 too. If any of these topics don’t show up here, they almost always show up in Q10 or Q11. 

• Chemical equilibrium (comes up most years as Q7 or Q9) 

○ Equilibrium constant calculations – guaranteed* 

○ Using Le Châtelier’s Principle to explain how different factors affect the rates of reaction 

○ Haber and Contact process 

• Rates of reaction: instantaneous rates of change, theories of catalysis, factors affecting the rate of reaction. 
• Acids and Bases/pH Calculations 

○ Arrhenius vs Brønsted-Lowry 

○ Conjugate acids and bases 

○ Calculations with acid dissociation constants and pH equation 

• Water: Dissolved oxygen, water and sewage treatment, hardness of water, suspended/dissolved solid calculations 

Question 10,11 

• Organic chemistry – almost every year 
• Stoichiometry – a question every year* 
• Redox numbers + balancing redox reactions 
• Gas laws 
• Bonding – forces, electronegativity, electronic structure 
• Radioactivity (could also appear in Q5) 
• Q11 (d) will examine options 

General patterns of LC Chemistry questions

• For experimental questions, question 1 is a titration, question 2 is based on organics and question 3 is another experiment.
• Titrations:
  • Determination of the concentration of ethanoic acid in vinegar
  • Determination of the amount of water of crystallisation in washing crystals
  • Potassium manganate – ammonium iron (ii) sulfate titration
  • Estimation of iron in an iron tablet
  • Iodine – thiosulfate titration
  • Determination of the percentage of hypochlorite in bleach
  • Estimation of the total hardness of a water sample
  • Estimation of dissolved oxygen by redox titration
  • Standardisation of a hydrochloric acid solution using a standard solution of sodium carbonate
• Organics experiments:
  • Recrystallisation and melting point determination of benzoic acid
  • Preparation and properties of ethyne
  • Extraction of clove oil from cloves
  • Preparation of soap
  • Preparation and properties of ethene
  • Properties of ethanal
  • Properties of ethanoic acid
  • Preparation of benzoic acid from phenylmethanol
  • Separation of a mixture of indicators using chromatography
• Some other experiments that are likely to come up (in question 3):
  • Test for anions
  • Estimation of the relative molecular mass of a volatile liquid
  • Determination of free chlorine in swimming pool water
  • Determination of total suspended solids, dissolved solids and pH in a water sample
• Question 4 consists of short questions based on various topics of the course.
• Question 5 topics include:
  • Elements and the periodic table
  • The atom
  • Radioactivity
  • Electronic structure of atoms
  • Ionic and covalent bonding
  • Shapes of molecules and intermolecular forces
• Question 6 is based on fuels and heats of reaction.
• Question 8 is based on organic chemistry.
• The topics of acids and bases, pH, chemical equilibrium and rates of a reaction usually make an appearance somewhere in the long questions. The topics of acids and bases and pH are usually linked in one single long question.
• One of the parts of question 10 will usually be based on organic chemistry or fuels and heats of reaction.
• One of the parts of question 10 or 11 will usually be stoichiometry (calculations based on chemical equations) and another part will usually be based on oxidation and reduction.
• The topics of shapes of molecules, ionic and covalent bonding, intermolecular forces, the atom and radioactivity will usually appear somewhere in the long questions. They are most likely to come up as parts of question 10 or 11.
• Question 11(c) A is based on either atmospheric chemistry or industrial chemistry.
• Question 11(c) B is based on crystals, polymers or metals.

2025:

2023:
Q1: Potassium manganate-ammonium iron (II) sulfate titration
Q2: Preparation of ethyne
Q3: Determination of the heat of reaction of hydrochloric acid with sodium hydroxide
Q4: Short questions on various topics
Q5: Electronic structure and Electronegativity
Q6: Fuels and heats of reaction
Q7: Acids/Bases/pH and Water
Q8: Organic chemistry
Q9: Chemical equilibrium
Q10: Benzene, Stoichiometry, Radioactivity
Q11: Gas laws, Electrolysis, Rates of reactions, Options

2022:
Q1: Estimation of the total hardness of a water sample
Q2: Ethene, Benzoic acid
Q3: Rates of reactions: decomposition of hydrogen peroxide
Q4: Short questions on various topics
Q5: Electronic structure and Radioactivity
Q6: Fuels and heats of reactions
Q7: Chemical equilibrium
Q8: Organic chemistry
Q9: Acids/Bases/pH
Q10: Gas laws, Electronegativity, Stoichiometry
Q11: Balancing redox equations, Properties of ethanal, Rates of reactions, Options

2021:
Q1: Bleach
Q2: Soap
Q3: Test for anions
Q4: Short questions on various topics
Q5: History/trends of periodic table

Q6: Fuels and heats of reactions
Q7: Acids/Bases/pH
Q8: Organic chemistry
Q9: Chemical equilibrium
Q10: Electron structure, Rates of reactions, Stoichiometry
Q11: Ethene, Water, Electron structure/Radioactivity

2020:
Q1: Washing crystals
Q2: Benzoic acid
Q3: Rates of reactions: temperature vs rate
Q4: Short questions on various topics
Q5: Electronic structure
Q6: Fuels and heats of reactions
Q7: Acids/Bases/pH
Q8: Organic chemistry
Q9: Chemical equilibrium
Q10: Water, Balancing redox equations, Stoichiometry
Q11: Electronegativity, Empirical/Molecular formula, Options

	2019	2018	2017	2016	2015	2014
Experimental Questions:	To measure the amount of dissolved oxygen in a sample of water by means of a redox titration	Estimation of the total hardness of a water sample/ Test for anions	Potassium manganate-ammonium iron (ii) sulfate titration	Determination of the concentration of ethanoic acid in vinegar	Iodine-thiosulfate titration	Determination of the amount of water of crystallisation in washing crystals
	Properties of ethanoic acid/ ethanal/ ethanol/ Preparation of ethene	Preparation of soap/ Extraction of clove oil from cloves/ Recrystallisation and melting point determination of benzoic acid	Preparation and properties of ethyne/ ethene	Properties of ethane/ ethanal/ ethanoic acid/ Recrystallisation and melting point determination of benzoic acid	Preparation of benzoic acid/ Recrystallisation and melting point determination	Preparation of soap
	To measure the relative molecular mass of a volatile liquid	Determination of the heat of reaction of hydrochloric acid with sodium hydroxide	The effect of temperature and concentration on the rate of a reaction	Measuring the rate of production of oxygen	Determination of free chlorine/ Suspended solids/ Dissolved solids/ Water hardness in a water sample	The effect of temperature and concentration on the rate of a reaction
Question 4:	Short questions on various topics	Short questions on various topics	Short questions on various topics	Short questions on various topics	Short questions on various topics	Short questions on various topics
Long Questions:	Periodic Table/ Trends in the Periodic Table	The atom/ Radioactivity	Electronic structure of atoms	Electronic structure of atoms	The atom/ Radioactivity/ Electronic structure of atoms	Electronic structure of atoms
	Fuels and heats of reaction	Fuels and heats of reaction	Fuels and heats of reaction	Fuels and heats of reaction	Fuels and heats of reaction	Fuels and heats of reaction
	Acids and bases/ pH/	Rates of a reaction	Chemical Equilibrium	Chemical Equilibrium	Rates of a reaction	Acids and bases/ pH/ Test for anions/ Water
	Organic Chemistry – alcohols	Organic Chemistry/ Intermolecular forces	Organic Chemistry	Organic Chemistry	Organic Chemistry/ Intermolecular forces	Organic Chemistry
	Rates of Reaction/ Chemical Equilibrium	Chemical Equilibrium	Acids and bases/ pH	Water	Acids and bases/ pH	Chemical equilibrium/ Rates of a reaction
Long Questions with options (Q10 & 11):	Organic Chemistry – substitution reactions	Fuels and heats of reaction	Estimation of the relative molecular mass of a volatile liquid	pH	Fuels and heats of reaction	Organic Chemistry
	Electronic structure of atoms	Electronic structure of atoms	The atom/ Radioactivity	Oxidation and reduction	Oxidation and reduction	The atom
	Stoichiometry	Stoichiometry	Organic Chemistry	Radioactivity	Stoichiometry	Oxidation and reduction
	Chemical bonding – electronegativity/ shapes of molecules	Shapes of Molecules/ Intermolecular forces	Stoichiometry	Stoichiometry	Elements and the periodic table/ Ionic and covalent bonding	Ionic and covalent bonding/ Shapes of molecules/ Intermolecular forces
	Chemical Equilibrium	Acids and bases/ pH	Ionic and covalent bonding	Shapes of Molecules/ Intermolecular forces	Chemical Equilibrium	Stoichiometry
Option (Q11c A&B):	Atmospheric Chemistry	Industrial Chemistry	Atmospheric Chemistry	Atmospheric Chemistry	Atmospheric Chemistry	Atmospheric Chemistry
	Crystals	Metals	Polymers	Metals	Metals	Crystals

 

Deferred papers and their impact on the main sitting of the Leaving Cert Chemistry exam

Do the deferred papers affect predictions? With a sample size of two, it’s hard to say. However, with the experiments, you can take note of the following: an experiment on a deferred paper has never appeared on the next year’s paper. In other words, the 2023 deferred paper and the 2024 paper don’t have any experiments in common. The same goes for the 2022 deferred paper and the 2023 paper.

Track record

2025: what we predicted

Experiment 1: Titration

• Iodine-thiosulfate titration
• Dissolved oxygen
• Water crystals

Experiment 2: Organic Chemistry

• Clove oil
• Recrystallisation of benzoic acid (melting point)
• Ethene/Ethyne

Experiment 3: Other Experiments

• Measurement of molecular mass of a volatile liquid
• Suspended/Dissolved solids + pH of water
• Concentration of free chlorine

Question 4: Short questions based on various topics

Question 5:

• Mass spectrometry
• Periodic table e.g. Mendeleev
• Flame tests
• Structure of atom

Question 6: Fuels and heats of reaction

• Thermochemistry calculations
• Fractional distillation of crude oil
• IUPAC naming
• Bomb calorimeter

Question 8: Organic chemistry

• IUPAC naming
• Ethene and bromine mechanism
• Recognising different types of organic reactions
• Properties of different families of compounds e.g. esters, alcohols, etc.
• Acidic nature of organic compounds

Questions 7,9:

• Chemical equilibrium: Le Chatelier’s principle, calculations, factors affecting rates of reactions, equilibrium constant, Haber and Contact process
• Water: Dissolved oxygen, water and sewage treatment, hardness of water, suspended/dissolved solid calculations

Question 10,11:

• Radioactivity
• Acids/Bases and pH calculations
• Stoichiometry
• Electronegativity + electronic structure
• Chromatography
• Gas laws
• Q11 (d) will examine options

2024: what we predicted

Experiment 1: Titration

• Titration to determine the concentration of ethanoic acid in vinegar
• Determination of the amount of water of crystallisation in washing crystals
• Iodine-thiosulfate titration

Experiment 2: Organic Chemistry

• Benzoic acid
• Extraction of clove oil from cloves
• Soap

Experiment 3: Other Experiments

• Measurement of molecular mass of a volatile liquid
• The effect of temperature and concentration on the rate of a reaction
• Estimation of the concentration of free chlorine in swimming-pool water

Question 5:

• Mass spectrometry
• Periodic table e.g. Mendeleev
• Bohr model of the atom
• Flame tests

Question 6: Fuels and heats of reaction

• Thermochemistry calculations
• Fractional distillation of crude oil
• IUPAC names of compounds
• Bomb calorimeter

Question 8: Organic chemistry

• IUPAC names of compounds
• Addition reactions – Ethene and bromine
• Properties of different families of compounds e.g. esters, alcohols, etc.

Questions 7,9:

• Chemical equilibrium: Le Chatelier’s Principle, Calculations, Factors affecting rates of reactions
• Water: Dissolved oxygen, Water and sewage treatment, Hardness of water

Question 10,11:

• Radioactivity
• Acids/Bases and pH calculations
• Stoichiometry
• Balancing redox equations
• Ionic/covalent bonding
• Chromatography
• Q11 (d) will examine options

2023: what we predicted

For 2023, it is not mandatory to answer 2 experiment questions as it has been in previous years.

While it is impossible to be certain of what will be on the paper, here are topics to pay special attention to for 2023:

Experiment 1: Titration

• Titration to determine the concentration of ethanoic acid in vinegar
• To prepare a solution of sodium hydroxide and standardise it with a standard hydrochloric acid solution to prepare sodium chloride
• Titration to determine the amount of iron in an iron tablet

Experiment 2: Organic Chemistry

• Reactions of ethanal/ethanoic acid
• Extraction of clove oil from cloves
• Preparation of benzoic acid

Experiment 3: Other experiments

• Estimation of the concentration of free chlorine in swimming-pool water
• Measurement of molecular mass of a volatile liquid
• Paper chromatography
• Flame tests/tests for anions

Question 4

• Answer 8 short questions from 12 on various aspects of the course
• Question 4(l) will be based on Options

Question 5

• Trends in the periodic table
• Ionic and covalent bonding
• Electronic structure of atoms

Question 6 – Fuels and Heats of Reaction

• Fractional distillation of crude oil
• IUPAC names of compounds
• Heat of combustion/formation calculation

Question 7

• Bronsted-Lowry vs Arrhenius theory of acids and bases
• pH calculations
• Le Chatelier’s principle

Question 8 – Organic Chemistry

• Properties of different families of compounds e.g. alcohols, aldehydes, carboxylic acids
• IUPAC names of compounds
• Substitution/addition/elimination reactions

Question 9

• Water
• Chemical equilibrium calculations
• Haber/Contact processes

Question 10 – parts a, b, c

• Rates of reaction
• Stoichiometry
• Water
• History of the atom

Question 11 – parts a, b, c, d

• Radioactivity
• Oxidation and reduction
• Mass spectrometry
• Part (d) will examine Options

2022: what we predicted

Experiment 1: Titration

• Estimation of iron in an iron tablet
• Iodine-thiosulfate titration
• Titration to determine the concentration of ethanoic acid in vinegar

Experiment 2: Organic Chemistry

• Preparation and properties of ethyne/ethene
• Reactions of ethanal/ethanoic acid
• Extraction of clove oil from cloves

Experiment 3: Other experiments

• Determination of the heat of reaction of hydrochloric acid with sodium hydroxide
• Estimation of the concentration of free chlorine in swimming-pool water
• Monitor the rate of production of oxygen from hydrogen peroxide using manganese dioxide as a catalyst

Question 4

• Answer 8 short questions from 12 on various aspects of the course
• Question 4(l) will be based on Options

Question 5

• Mass spectrometry
• Radioactivity
• Ionic and covalent bonding

Question 6 – Fuels and Heats of Reaction

• Fractional distillation of crude oil
• IUPAC names of compounds
• Heat of combustion/formation calculation

Question 7 – Acids and Bases

• Bronsted-Lowry vs Arrhenius theory of acids and bases
• Self-ionisation of water
• pH calculations

Question 8 – Organic Chemistry

• Properties of different families of compounds e.g. alcohols, aldehydes, carboxylic acids
• Substitution/addition/elimination reactions

Question 9 – Chemical Equilibrium

• Le Chatelier’s principle
• Chemical equilibrium calculations
• Haber/Contact processes

Question 10 – parts a, b, c

• Rates of reaction
• Stoichiometry
• Water
• History of the atom

Question 11 – parts a, b, c, d

• Trends in the periodic table
• Gases
• Oxidation and reduction
• Part (d) will examine Options

2021: what we predicted

Experiment 1: Titration

• Determination of the percentage of hypochlorite in bleach
• Estimation of iron in an iron tablet
• Iodine-thiosulfate titration

Experiment 2: Organic Chemistry

• Preparation and properties of ethyne/ethene
• Preparation of soap
• Properties of ethanoic acid/ethanal

Experiment 3: Mixed

• Determination of the concentration of free chlorine in swimming pool water
• Measuring the rate of production of oxygen from hydrogen peroxide
• Halogens as oxidising agents/displacement reactions of metals

Question 4:

• Short questions on various aspects of the course (Options will not be examined)

Question 5:

• History of the atom e.g. discovery of the proton, neutron, electron
• Mass spectrometry, radioactivity

Question 6:

• Fuels and Heats of Reaction – oil refining, petrol, hydrogen as a fuel, heat of combustion

Question 7:

• Acids and bases

Question 8:

• Organic chemistry – properties of different families of compounds, addition/substitution/elimination reactions

Question 9:

• Chemical equilibrium

Questions 10 & 11 (multiple parts):

• Oxidation/reduction reactions
• Stoichiometry
• Chemical bonding – shapes of molecules, electronegativity etc.
• Rates of reaction
• Water – biochemical oxygen demand, wastewater treatment

2020: what we predicted

Experiment 1: Titration

• Determine the amount of water of crystallisation in hydrated sodium carbonate
• Determine the amount of iron in an iron tablet
• Determine the percentage (w/v) of sodium hypochlorite in bleach 
• Determine the concentration of ethanoic acid in vinegar

Experiment 2: Organic Chemistry 

• Preparation of benzoic acid from phenylmethanol
• Preparation and properties of ethyne and ethene
• To separate a mixture of substances using paper chromatography

Experiment 3: Mix

• Effect of concentration/temperature on the rate of reaction
• Estimate the concentration of free chlorine in swimming-pool water
• Illustration of Le Chatelier’s Principle 
• Halogens as Oxidising Agents/ Displacement Reactions of Metals/ Test for Anions

Question 4:

• Short questions on various aspects of the course

Question 5: 

• Electronic structure of atoms eg. orbitals/ s, p configuration etc. 
• History of the atom eg. Dalton’s Atomic Theory, Discovery of the proton/neutron/electron, Thompson’s plum pudding model, Bohr Model etc. 
• Periodic Table eg. Triads/Octaves/Mendeleev vs Moseley
• Trends in the Periodic Table

Long Questions 6-9: 

• Fuels and Heats of Reaction
• Chemical Equilibrium
• Rates of Reaction
• Water 

Long Questions with options (Q10 & 11): 

• Stoichiometry 
• Oxidation/Reduction
• Ionic and covalent bonding
• Acids and Bases/ pH and Indicators

Options (11c A & B): 

• QA: Atmospheric Chemistry  
• QB: Polymers/Metals

2019: what we predicted

For your reference, this is what we had predicted in 2019:

• Determination of the amount of water of crystallisation in washing crystals
• Determination of the percentage of hypochlorite in bleach
• Estimation of dissolved oxygen by redox titration
• Standardisation of a hydrochloric acid solution using a standard solution of sodium carbonate
• Properties of ethanal
• Properties of ethanoic acid
• Preparation of benzoic acid from phenylmethanol
• Separation of a mixture of indicators using chromatography
• Elements and the periodic table
• Electronic structure of atoms