Calcium carbonate reacts with hydrochloric acid to produce calcium chloride, water and carbon dioxide. Explain why a student should check the hazard information for hydrochloric acid before carrying out this reaction, and describe one precaution the student should take.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A student is planning to react calcium carbonate with hydrochloric acid in a school laboratory.
Model answer (4 marks)
Hydrochloric acid is corrosive and can irritate skin and eyes. Checking the hazard information tells the student how the acid could harm them and what risks are present, so they can work safely. The student should wear safety goggles. Goggles prevent acid splashes from reaching the eyes, avoiding burns and irritation.
Examiner tips
- Use the word ‘corrosive’ or ‘irritant’ when describing the hazard.
- Explain that checking the SDS tells you the risks and how to mitigate them.
- Mention a specific precaution (e.g. goggles) and justify it by linking to the corrosive nature of the acid.
Common mistakes
- Using vague terms like ‘dangerous’ instead of ‘corrosive’ or ‘irritant’.
- Failing to explain why the precaution is relevant to the hazard.
- Omitting the hazard information check step.
Mark scheme (4 marks)
- Hydrochloric acid is corrosive / irritant (accept: harmful)
- Checking hazard information tells the student how the chemical could harm them / what risks are present so they can work safely
- Names a suitable precaution linked to the corrosive / irritant nature of hydrochloric acid, e.g. wearing safety goggles / eye protection
- Explanation of why that precaution is appropriate, e.g. to prevent acid splashing into eyes / onto skin causing burns / irritation
Key terms in this question
Related
- All Edexcel GCSE Chemistry (1CH0) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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