Magnesium sulfate is a salt used in medicine. It can be made by reacting magnesium carbonate with dilute sulfuric acid. Explain why magnesium carbonate is described as a base, and name the type of reaction that occurs when it reacts with dilute sulfuric acid.

Eduqas GCSE Chemistry — 2.2 Acids, bases and salts · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Magnesium carbonate is a white powder that reacts with dilute sulfuric acid to produce magnesium sulfate solution, water and carbon dioxide gas.

Model answer (4 marks)

Magnesium carbonate is a base because it neutralises an acid. When it reacts with dilute sulphuric acid it donates carbonate ions that combine with hydrogen ions to form water and carbon dioxide, while the remaining ions form the salt magnesium sulphate. The reaction is therefore a neutralisation reaction, giving the salt, water and CO₂ as products.

Examiner tips

  • Use the word ‘base’ and explain neutralisation; mention the products (salt, water, CO₂).
  • Show the reaction as a neutralisation between a carbonate and a sulphuric acid.
  • Include the salt name (magnesium sulphate) to demonstrate understanding of products.

Common mistakes

  • Calling magnesium carbonate an acid or failing to identify it as a base.
  • Describing the reaction as a decomposition or combustion instead of neutralisation.

Mark scheme (4 marks)

  1. A base is a substance that neutralises an acid
  2. Magnesium carbonate neutralises the sulfuric acid (so it acts as a base)
  3. The type of reaction is neutralisation
  4. A salt (magnesium sulfate) and water are products of the reaction (alongside carbon dioxide)

Key terms in this question

base · salt · acid

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