State two characteristic reactions of acids with metals and describe what is observed in each reaction. For each reaction, name one product formed.

Cambridge International IGCSE Chemistry (0620) — 7.1 The characteristic properties of acids and bases · State · 4 marks · View as Markdown

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

Model answer (4 marks)

1. Acid + metal:

Observation: effervescence (bubbles) as hydrogen gas is released.
Product: hydrogen gas and a metal salt.

2. Acid + metal carbonate (or oxide/hydroxide):

Observation: effervescence (bubbles) as carbon dioxide gas is released (or the solid dissolves).
Product: carbon dioxide gas (and a metal salt, plus water if oxide/hydroxide).

Examiner tips

  • Use the word "effervescence" to show bubbles. Include the gas produced (H₂ or CO₂) and the salt formed. Mention the solid dissolving for oxides/hydroxides.
  • common_mistakes
  • :
  • Writing "gas released" without naming H₂ or CO₂. For the carbonate reaction, forgetting to mention the salt. Using "gas" instead of "hydrogen" or "carbon dioxide".

Mark scheme (4 marks)

  1. Acids react with (reactive) metals
  2. Bubbles / effervescence observed; hydrogen gas produced
  3. Acids react with metal carbonates (or metal oxides / metal hydroxides)
  4. Correct observation and named product for the second reaction — e.g. for carbonates: bubbles/effervescence and carbon dioxide produced; for oxides/hydroxides: solid dissolves and a salt (and water) is formed

Key terms in this question

acid · metal

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