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AQA GCSE Chemistry Smart practice A mixed round aimed at your weak spots
Unit 1
Atomic structure and the periodic table
A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes
Atoms, elements and compounds
0%
Mixtures
0%
The development of the model of the atom
0%
Relative electrical charges of subatomic particles
0%
Size and mass of atoms
0%
Relative atomic mass
0%
Electronic structure
0%
The periodic table
The periodic table
0%
Development of the periodic table
0%
Metals and non-metals
0%
Group 0
0%
Group 1
0%
Group 7
0%
Properties of transition metals (chemistry only)
Comparison with Group 1 elements (chemistry only)
0%
Typical properties (chemistry only)
0%
Unit 2
Bonding, structure, and the properties of matter
Chemical bonds, ionic, covalent and metallic
Chemical bonds
0%
Ionic bonding
0%
Ionic compounds
0%
Covalent bonding
0%
Metallic bonding
0%
How bonding and structure are related to the properties of substances
The three states of matter
0%
State symbols
0%
Properties of ionic compounds
0%
Properties of small molecules
0%
Polymers
0%
Giant covalent structures
0%
Properties of metals and alloys
0%
Metals as conductors
0%
Structure and bonding of carbon
Diamond
0%
Graphite
0%
Graphene and fullerenes
0%
Bulk and surface properties of matter including nanoparticles (chemistry only)
Sizes of particles and their properties (chemistry only)
0%
Uses of nanoparticles (chemistry only)
0%
Unit 3
Quantitative chemistry
Chemical measurements, conservation of mass and the quantitative interpretation of chemical equations
Conservation of mass and balanced chemical equations
0%
Relative formula mass
0%
Mass changes when a reactant or product is a gas
0%
Chemical measurements
0%
Use of amount of substance in relation to masses of pure substances
Moles (HT only)
0%
Amounts of substances in equations (HT only)
0%
Using moles to balance equations (HT only)
0%
Limiting reactants (HT only)
0%
Concentration of solutions
0%
Yield and atom economy of chemical reactions (chemistry only)
Percentage yield (chemistry only)
0%
Atom economy (chemistry only)
0%
Using concentrations of solutions in mol/dm³ (chemistry only) (HT only)
0%
Use of amount of substance in relation to volumes of gases (chemistry only) (HT only)
0%
Unit 4
Chemical changes
Reactivity of metals
Metal oxides
0%
The reactivity series
0%
Extraction of metals and reduction
0%
Oxidation and reduction in terms of electrons (HT only)
0%
Reactions of acids
Reactions of acids with metals
0%
Neutralisation of acids and salt production
0%
Soluble salts
0%
The pH scale and neutralisation
0%
Titrations (chemistry only)
0%
Strong and weak acids (HT only)
0%
Electrolysis
The process of electrolysis
0%
Electrolysis of molten ionic compounds
0%
Using electrolysis to extract metals
0%
Electrolysis of aqueous solutions
0%
Representation of reactions at electrodes as half equations (HT only)
0%
Unit 5
Energy changes
Exothermic and endothermic reactions
Energy transfer during exothermic and endothermic reactions
0%
Reaction profiles
0%
The energy change of reactions (HT only)
0%
Chemical cells and fuel cells (chemistry only)
Cells and batteries (chemistry only)
0%
Fuel cells (chemistry only)
0%
Unit 6
The rate and extent of chemical change
Rate of reaction
Calculating rates of reactions
0%
Factors which affect the rates of chemical reactions
0%
Collision theory and activation energy
0%
Catalysts
0%
Reversible reactions and dynamic equilibrium
Reversible reactions
0%
Energy changes and reversible reactions
0%
Equilibrium
0%
The effect of changing conditions on equilibrium (HT only)
0%
The effect of changing concentration (HT only)
0%
The effect of temperature changes on equilibrium (HT only)
0%
The effect of pressure changes on equilibrium (HT only)
0%
Unit 7
Organic chemistry
Carbon compounds as fuels and feedstock
Crude oil, hydrocarbons and alkanes
0%
Fractional distillation and petrochemicals
0%
Properties of hydrocarbons
0%
Cracking and alkenes
0%
Reactions of alkenes and alcohols (chemistry only)
Structure and formulae of alkenes (chemistry only)
0%
Reactions of alkenes (chemistry only)
0%
Alcohols (chemistry only)
0%
Carboxylic acids (chemistry only)
0%
Synthetic and naturally occurring polymers (chemistry only)
Addition polymerisation (chemistry only)
0%
Condensation polymerisation (HT only) (chemistry only)
0%
Amino acids (HT only) (chemistry only)
0%
DNA (deoxyribonucleic acid) and other naturally occurring polymers (chemistry only)
0%
Unit 8
Chemical analysis
Purity, formulations and chromatography
Pure substances
0%
Formulations
0%
Chromatography
0%
Identification of common gases
Test for hydrogen
0%
Test for oxygen
0%
Test for carbon dioxide
0%
Test for chlorine
0%
Identification of ions by chemical and spectroscopic means (chemistry only)
Flame tests (chemistry only)
0%
Metal hydroxides (chemistry only)
0%
Carbonates (chemistry only)
0%
Halides (chemistry only)
0%
Sulfates (chemistry only)
0%
Instrumental methods (chemistry only)
0%
Flame emission spectroscopy (chemistry only)
0%
Unit 9
Chemistry of the atmosphere
The composition and evolution of the Earth's atmosphere
The proportions of different gases in the atmosphere
0%
The Earth's early atmosphere
0%
How oxygen increased
0%
How carbon dioxide decreased
0%
Carbon dioxide and methane as greenhouse gases
Greenhouse gases
0%
Human activities which contribute to an increase in greenhouse gases in the atmosphere
0%
Global climate change
0%
The carbon footprint and its reduction
0%
Common atmospheric pollutants and their sources
Atmospheric pollutants from fuels
0%
Properties and effects of atmospheric pollutants
0%
Unit 10
Using resources
Using the Earth's resources and obtaining potable water
Using the Earth's resources and sustainable development
0%
Potable water
0%
Waste water treatment
0%
Alternative methods of extracting metals (HT only)
0%
Life cycle assessment and recycling
Life cycle assessment
0%
Ways of reducing the use of resources
0%
Using materials (chemistry only)
Corrosion and its prevention (chemistry only)
0%
Alloys as useful materials (chemistry only)
0%
Ceramics, polymers and composites (chemistry only)
0%
The Haber process and the use of NPK fertilisers (chemistry only)
The Haber process (chemistry only)
0%
Production and uses of NPK fertilisers (chemistry only)
0%
Avg
score:
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Topics
done:
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Strong and weak acids (HT only)

Practise 26 exam-style questions on Strong and weak acids (HT only) for AQA GCSE Chemistry. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.

  • 26 questions
  • 1–6 marks each
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20 questions, marked as you go

Sample questions with model answers

Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.

Question 1

2 marks

Hydrochloric acid is a strong acid and ethanoic acid is a weak acid.

Explain the difference between a strong acid and a weak acid.

Model answer

A strong acid, such as hydrochloric acid, is completely ionised in aqueous solution, so all of its molecules release H⁺ ions. A weak acid, such as ethanoic acid, is only partially ionised, so only a small proportion of its molecules release H⁺ ions.

Explanation

Acid strength is about the degree of ionisation, not about how much acid is dissolved. Do not mix up 'strong' with 'concentrated' or 'weak' with 'dilute'.

Mark scheme
  1. 1 mark

    a strong acid is completely ionised in aqueous solution

    allow fully ionised / fully dissociated; allow all molecules release H⁺ ions

  2. 1 mark

    a weak acid is only partially ionised in aqueous solution

    allow only some molecules release H⁺ ions; do not accept answers about concentration (amount of acid per volume)

Question 2

2 marks

Four solutions all have a concentration of 0.1 mol/dm³:

ethanoic acid
nitric acid
sodium chloride solution
sodium hydroxide solution

List the four solutions in order of increasing hydrogen ion concentration, starting with the lowest.

Model answer

sodium hydroxide solution (lowest), sodium chloride solution, ethanoic acid, nitric acid (highest)

Explanation

The higher the hydrogen ion concentration, the lower the pH. Sodium hydroxide is alkaline (pH about 13), sodium chloride is neutral (pH 7), ethanoic acid is a weak acid (pH about 3) and nitric acid is a strong acid (pH 1), so this is also the order of decreasing pH.

Mark scheme
  1. 1 mark

    sodium hydroxide solution first (lowest), then sodium chloride solution

    full order: sodium hydroxide, sodium chloride, ethanoic acid, nitric acid; allow the complete order written from highest to lowest only if clearly stated as such

  2. 1 mark

    ethanoic acid next, then nitric acid last (highest)

Question 3

3 marks

A 0.1 mol/dm³ solution of nitric acid has a pH of 1. A 0.1 mol/dm³ solution of citric acid has a pH of 2.

How many times greater is the hydrogen ion concentration in the nitric acid than in the citric acid? Which acid is the weaker acid? Explain your answer.

Model answer

The pH differs by one unit, so the hydrogen ion concentration in nitric acid is 10 times greater. Citric acid is the weaker acid: at the same concentration it has a higher pH because it is only partially ionised, so it releases fewer hydrogen ions.

Explanation

A difference of one pH unit means a tenfold difference in hydrogen ion concentration. Comparing acids of the same concentration is a fair test of strength, because any difference in pH must come from the degree of ionisation.

Mark scheme
  1. 1 mark

    10 times

  2. 1 mark

    citric acid is weaker

  3. 1 mark

    because at the same concentration it is only partially ionised / releases fewer H⁺ ions / has a higher pH

Question 4

4 marks

Solution P is 2.0 mol/dm³ ethanoic acid. Solution Q is 0.1 mol/dm³ hydrochloric acid.

A student predicted that solution P would have the lower pH because it is more concentrated. The student then measured the pH values: P had a pH of 2 and Q had a pH of 1.

Explain why the student's prediction was wrong.

Model answer

Solution P is more concentrated, as it contains more moles of acid per dm³. However, ethanoic acid is a weak acid, so only a small fraction of its molecules ionise. Hydrochloric acid is a strong acid and is completely ionised. pH depends on the concentration of hydrogen ions, and solution Q actually has the higher hydrogen ion concentration (10 times higher), so Q has the lower pH.

Explanation

The student only thought about concentration and ignored strength. Both the amount of acid dissolved and the fraction that ionises decide the hydrogen ion concentration, and so the pH.

Mark scheme
  1. 1 mark

    P does contain more moles of acid per dm³ / is more concentrated

  2. 1 mark

    ethanoic acid is a weak acid / only partially ionised

  3. 1 mark

    hydrochloric acid is a strong acid / completely ionised

  4. 1 mark

    pH depends on the concentration of hydrogen ions, which is higher in Q (10 times higher)

    allow pH depends on both the concentration and the strength of the acid

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