1 Calcium carbonate breaks down on heating to produce calcium oxide and carbon dioxide gas.
CaCO3 → CaO + CO2
A student heats 15 g of calcium carbonate strongly in a crucible.
Relative atomic masses (Ar): Ca = 40, C = 12, O = 16.
a Calculate the number of moles in 15 g of calcium carbonate. 0.15 (2 marks)
b Use your answer to part a to determine the number of moles of calcium oxide that will be produced. (1 mark)
c Calculate the mass of calcium oxide produced by this reaction. (2 marks)

2 A student is preparing a sample of sodium nitrate, NaNO3.
She mixes 17 g of sodium oxide with an excess of nitric acid. The equation for the reaction is:
Na2O + 2HNO3 → 2NaNO3 + H2O
Relative atomic masses (Ar): Na = 23, O = 16, N = 14, H = 1.
a Calculate the number of moles in 17 g of sodium oxide. (2 marks)
b Calculate the maximum mass of sodium nitrate that can be produced in this reaction. (3 marks)

3 Aluminium and iron oxide (Fe2O3) react together to produce aluminium oxide (Al2O3). The equation for the reaction is:
2Al + Fe2O3 → Al2O3 + 2Fe
Calculate the mass of iron that is produced by reacting 20 g of iron oxide with an excess of aluminium.
Relative atomic masses (Ar): Al = 27, O = 16, Fe = 56. (4 marks)