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Subjects · Leaving Certificate

Leaving Cert Chemistry

What has come up on the Chemistry papers (2016–2026), topic by topic, with step-by-step practice at Higher Level and Ordinary Level.

Higher Level Ordinary Level

Chemistry, Higher Level(6 marks)

Three quick ones from the Chemistry topics that come up most.

(a)Bronsted-Lowry definition of an acid?
  1. A proton acceptor
  2. A proton donor
  3. An electron pair donor
(b)Relative charge on a neutron?
  1. -1
  2. +1
  3. 0
(c)At dynamic equilibrium, the rates of the forward and reverse reactions are?
  1. Equal
  2. Forward faster than reverse
  3. Both zero
Show the answers

(a) A proton donor

(b) 0

(c) Equal

Your turn: pick the answer for each one.

Higher Level

400 flash cards and 240 step-by-step drill questions at Higher Level.

What comes up

How many of the last 10 Chemistry Higher Level papers asked each topic.

TopicAskedLast seenHow often
Mandatory experiments banker10 of 102026
Atomic structure banker10 of 102026
Gas laws banker10 of 102026
The mole banker10 of 102026
Hydrocarbons banker10 of 102026
Organic reactions banker10 of 102026
Oxidation and reduction banker10 of 102026
Fuels and heats of reaction banker10 of 102026
Functional groups banker10 of 102026
Acids and bases banker10 of 102026
Rates of reaction banker10 of 102026
Water treatment banker10 of 102026
pH banker10 of 102026
Chemical equilibrium banker10 of 102026

More topics: Electronegativity, Shapes of molecules, Trends, Volumetric analysis, Electron configuration, Organic synthesis, Radioactivity, Instrumentation and separation, Formulas and equations, Intermolecular forces, Covalent bonding, Isomerism, Environmental chemistry, Concentration, Electrochemistry, The periodic table, Industrial chemistry.

These counts come from the 2016–2026 papers. June 2027 is the first exam on the new Chemistry specification, so read them as a guide to the core topics; the app follows the course for the June you sit.

Try three

The mole, 3 marks

0.2 mol of Mg is added to 0.3 mol of HCl. Mg + 2HCl -> MgCl2 + H2. Which reagent is limiting?

  1. Magnesium
  2. Neither of them
  3. Hydrochloric acid
Show the answer

Hydrochloric acid

0.2 mol of Mg would need 0.4 mol of HCl. Only 0.3 mol is present, so the acid runs out first and some magnesium is left.

Volumetric analysis, 3 marks

25.0 cm3 of NaOH needs 20.0 cm3 of 0.10 mol l⁻¹ HCl. Concentration of the NaOH?

  1. 0.10 mol l⁻¹
  2. 0.08 mol l⁻¹
  3. 0.125 mol l⁻¹
Show the answer

0.08 mol l⁻¹

n(HCl) = 0.10 x 0.0200 = 0.00200 mol. The ratio is 1:1, so c(NaOH) = 0.00200 / 0.0250 = 0.08 mol l⁻¹.

Chemical equilibrium, 3 marks

2CrO4 2- + 2H+ in equilibrium with Cr2O7 2- + H2O. NaOH is added to the orange solution. It turns?

  1. Yellow, as H+ is removed
  2. A deeper orange
  3. Green, as chromium is reduced
Show the answer

Yellow, as H+ is removed

OH- removes H+, so the equilibrium shifts left to replace it, forming yellow chromate ions.

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Ordinary Level

300 flash cards and 150 step-by-step drill questions at Ordinary Level.

What comes up

How many of the last 10 Chemistry Ordinary Level papers asked each topic.

TopicAskedLast seenHow often
Mandatory experiments banker10 of 102026
Fuels and heats of reaction banker10 of 102026
Hydrocarbons banker10 of 102026
Water treatment banker10 of 102026
Atomic structure banker10 of 102026
Gas laws banker10 of 102026
Concentration banker10 of 102026
Rates of reaction banker10 of 102026
The mole banker10 of 102026
Organic reactions banker10 of 102026
The periodic table banker10 of 102026
Chemical equilibrium banker10 of 102026
Covalent bonding banker10 of 102026
Electronegativity banker10 of 102026

More topics: Oxidation and reduction, pH, Volumetric analysis, Formulas and equations, Organic synthesis, Radioactivity, Functional groups, Acids and bases, Ionic bonding, Instrumentation and separation, Electrochemistry, Trends, Shapes of molecules, Electron configuration, Environmental chemistry, Isomerism, Industrial chemistry, Intermolecular forces, Lab safety, States of matter.

These counts come from the 2016–2026 papers. June 2027 is the first exam on the new Chemistry specification, so read them as a guide to the core topics; the app follows the course for the June you sit.

Try three

Concentration, 3 marks

0.5 mol of sodium chloride is dissolved to make 2 litres of solution. Concentration?

  1. 1.0 mol/L
  2. 2.5 mol/L
  3. 0.25 mol/L
Show the answer

0.25 mol/L

Concentration = moles divided by litres = 0.5 / 2 = 0.25 mol/L.

Volumetric analysis, 3 marks

10.0 cm3 of HCl is neutralised by 20.0 cm3 of 0.10 mol/L NaOH (1 to 1). Concentration of the HCl?

  1. 0.10 mol/L
  2. 0.20 mol/L
  3. 0.05 mol/L
Show the answer

0.20 mol/L

Moles NaOH = 0.020 x 0.10 = 0.002 = moles HCl. Concentration = 0.002 / 0.010 = 0.20 mol/L.

Gas laws, 3 marks

2H2 + O2 gives 2H2O (all gases). Volume of oxygen needed to react with 100 cm3 of hydrogen?

  1. 50 cm3
  2. 100 cm3
  3. 200 cm3
Show the answer

50 cm3

Gay-Lussac's law: gases react in simple volume ratios. H2 to O2 is 2 to 1, so 100 cm3 of H2 needs 50 cm3 of O2.

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