Reactions of acids with metals - AQA GCSE Chemistry Exam Questions

Practise 16 exam-style questions on Reactions of acids with metals 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.

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1–6 marks each
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16 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

Zinc reacts with dilute hydrochloric acid to produce zinc chloride and hydrogen.

Write a balanced symbol equation for this reaction.

Model answer

Zn + 2HCl → ZnCl₂ + H₂

Explanation

Zinc ions are Zn²⁺, so zinc chloride is ZnCl₂. Two molecules of HCl supply the two chlorine atoms, and their two hydrogen atoms form one H₂ molecule.

Mark scheme

1 mark
correct formulae: Zn + HCl → ZnCl₂ + H₂
1 mark
balanced: Zn + 2HCl → ZnCl₂ + H₂
allow multiples; ignore state symbols

Question 2

3 marks

Magnesium reacts with dilute hydrochloric acid to produce magnesium chloride solution and hydrogen gas.

Write a balanced symbol equation for this reaction. Include state symbols.

Model answer

Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g)

Explanation

Dilute hydrochloric acid and the salt solution are aqueous, magnesium is a solid and hydrogen is a gas. Mg²⁺ needs two Cl⁻ ions, so two HCl are needed to balance the equation.

Mark scheme

1 mark
correct formulae: Mg + HCl → MgCl₂ + H₂
1 mark
balanced: Mg + 2HCl → MgCl₂ + H₂
allow multiples
1 mark
state symbols: Mg(s), HCl(aq), MgCl₂(aq), H₂(g)
allow state symbols mark on an equation with correct formulae even if not balanced

Question 3

3 marks

1.2 g of magnesium reacts completely with excess dilute sulfuric acid:
Mg + H₂SO₄ → MgSO₄ + H₂

Calculate the mass of magnesium sulfate produced.
Relative atomic masses (Ar): O = 16, Mg = 24, S = 32

Model answer

moles of Mg = 1.2 ÷ 24 = 0.050 mol
From the equation, 1 mol Mg gives 1 mol MgSO₄, so moles of MgSO₄ = 0.050 mol
Mr of MgSO₄ = 24 + 32 + (4 × 16) = 120
mass of MgSO₄ = 0.050 × 120 = 6.0 g

Explanation

The acid is in excess, so the magnesium decides how much salt forms. The 1 : 1 ratio in the equation means the moles of salt equal the moles of magnesium.

Mark scheme

1 mark
moles of Mg = 1.2 ÷ 24 = 0.050
1 mark
Mr of MgSO₄ = 120
1 mark
mass = 0.050 × 120 = 6.0 (g)
allow ecf; allow 6; correct answer with no working scores 3 marks

Question 4

4 marks

Excess magnesium is added to 50.0 cm³ of 2.00 mol/dm³ hydrochloric acid:
Mg + 2HCl → MgCl₂ + H₂

Calculate the volume of hydrogen, in dm³, produced at room temperature and pressure.
The volume of one mole of any gas at room temperature and pressure is 24 dm³.

Model answer

moles of HCl = 2.00 × (50.0 ÷ 1000) = 0.100 mol
From the equation, 2 mol HCl give 1 mol H₂, so moles of H₂ = 0.0500 mol
volume of H₂ = 0.0500 × 24 = 1.2 dm³

Explanation

Magnesium is in excess, so the acid is the limiting reactant and decides how much hydrogen forms. Two moles of HCl are needed for each mole of hydrogen, so halve the moles of acid before converting to a volume.

Mark scheme

1 mark
moles of HCl = 2.00 × 0.0500 = 0.100
1 mark
moles of H₂ = 0.100 ÷ 2 = 0.0500
allow ecf
1 mark
volume = 0.0500 × 24
allow ecf
1 mark
1.2 (dm³)
allow 1.20; 2.4 dm³ (ratio not used) scores 3 marks; correct answer with no working scores 4 marks

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