A-LevelChemistryAtoms, molecules and stoichiometryOct/Nov 2017Paper 1 Q31 Mark
The airbags in cars contain sodium azide, NaN3, and an excess of potassium nitrate, KNO3. In a car accident, the reactions shown occur, producing nitrogen. This causes the airbag to inflate rapidly. 2NaN3 → 2Na + 3N2 10Na + 2KNO3 → K2O + 5Na2O + N2 How many moles of nitrogen gas are produced in total when 1 mol of sodium azide, NaN3, decomposes in an airbag?
A1.5
B1.6
C3.2
D4.0
✓ Correct Answer
The correct answer is B: 1.6
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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