A-Level UK (AQA, Edexcel, OCR) · Chemistry

Amount of substance

9 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 9 questions

  1. How many moles are there in 5.30 g of sodium carbonate, Na2CO3 (Mr = 106.0)?
  2. 25.0 cm3 of sodium hydroxide solution is neutralised by 20.0 cm3 of 0.100 mol dm-3 hydrochloric acid. What is the concentration of the sodium hydroxide?
  3. A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen by mass. What is its empirical formula? (Ar: C 12, H 1, O 16)
  4. 2.30 g of ethanol (Mr = 46.0) is oxidised to ethanoic acid (Mr = 60.0), and 1.80 g of ethanoic acid is collected. What is the percentage yield?
  5. What volume does 0.250 mol of gas occupy at room temperature and pressure (24.0 dm3 mol-1)?
  6. A gas of 2.00 dm3 is at 100 kPa and 300 K. How many moles does it contain? (R = 8.31 J K-1 mol-1)
  7. Calcium carbonate is decomposed: CaCO3 -> CaO + CO2. What is the atom economy for making CaO? (Mr: CaCO3 100, CaO 56, CO2 44)
  8. 2.40 g of magnesium (Ar = 24.0) reacts with excess hydrochloric acid. What volume of hydrogen forms at room temperature and pressure (24.0 dm3 mol-1)?
  9. 5.40 g of aluminium (Ar = 27.0) burns in excess chlorine: 2Al + 3Cl2 -> 2AlCl3. What mass of aluminium chloride (Mr = 133.5) forms?

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