A Levels Chemistry (9701)•9701/13/M/J/19

Explanation
Stoichiometry of CO-NO reaction in catalytic converter
Steps:
- Balanced equation: 2CO + 2NO → 2CO₂ + N₂ (NO in excess, so CO limiting).
- Moles of CO: 5.0 g / 28 g/mol = 0.179 mol.
- Moles CO₂ produced = 0.179 mol; mass = 0.179 × 44 g/mol = 7.9 g (≈8 g).
- Moles N₂ produced = 0.179 / 2 = 0.089 mol; mass = 0.089 × 28 g/mol = 2.5 g (≈2.4 g).
Why D is correct:
- Matches stoichiometric masses: 1:1 CO:CO₂ ratio and 2:1 CO:N₂ ratio from balanced equation.
Why the others are wrong:
- A: N₂ mass too high (ignores 2:1 CO:N₂ ratio).
- B: Lists NO as product (NO is reactant, not produced).
- C: Lists NO as product and underestimates CO₂ mass.
Final answer: D
Topic: Atoms, molecules and stoichiometry
Practice more A Levels Chemistry (9701) questions on mMCQ.me