26 Feb 2024 2 min read

Moles = Mass/Mr | AQA GCSE Chemistry Practice Questions

1) What mass of hydrogen is produced when 192 g of magnesium is reacted with hydrochloric acid?

Mg + 2 HCl → MgCl₂ + H₂ (3 marks)

2) What mass of oxygen is needed to react with 8.5 g of hydrogen sulphide (H₂S)?

2 H₂S + 3 O₂ → 2 SO₂ + 2 H₂O (3 marks)

3) What mass of potassium oxide is formed when 7.8 g of potassium is burned in oxygen?

4 K + O₂ → 2 K₂O (3 marks)

4) Railway lines are welded together by the Thermitt reaction, which produces molten iron. What mass of iron is formed from 1 kg of iron oxide?

Fe₂O₃ + 2 Al → 2 Fe + Al₂O₃ (3 marks)

5) What mass of oxygen is required to oxidise 10 g of ammonia to NO?

4 NH₃ + 5 O₂ → 4 NO + 6 H₂O (3 marks)

6) What mass of aluminium oxide is produced when 135 g of aluminium is burned in oxygen?

2 Al + 3 O₂ → Al₂O₃ (3 marks)

Limiting Reactant