Test on Mole concept
1.In industry calcium oxide is often used to remove water vapour from gas mixtures.
The water reacts to form calcium hydroxide.
The equation for the reaction of calcium oxide with water vapour is
CaO(s) + H2O(g) Ca(OH)2(s)
i) Calculate the relative formula masses of calcium oxide and water.
(Relative atomic masses: H = 1.0; O = 16; Ca = 40) 
ii) Use your answers to part (i) to calculate the minimum mass of water vapour needed to
react with 100g of calcium oxide. 
Carbon dioxide vapour can also be removed from gas mixtures by passing them over
calcium oxide. The carbon dioxide forms calcium carbonate.
d) Write the balanced equation for the reaction between calcium oxide and carbon dioxide. 
2. Dilute sulphuric acid and barium chloride solution react to form barium sulphate.
The equation for this reaction is
H2SO4(aq ) + BaCl2(aq) à BaSO4(s) + 2HCl(aq)
When an excess of barium chloride solution was added to 100 cm3 of dilute sulphuric acid,
2.80 g of barium sulphate was formed.
i) Calculate the number of moles of barium sulphate, BaSO4, present in the 2.80 g.
(Relative atomic masses: O = 16; S = 32; Ba = 137) 
ii) Use your answer to part i) to find the number of moles of sulphuric acid, H2SO4,
present in 100 cm3 of the acid. 
iii) Calculate the concentration of dilute sulphuric acid (H2SO4) in mol dm-3. 
3.12 g of anhydrous iron(II) sulfate was heated. Calculate the mass of iron(III) oxide
formed and the volume of sulfur trioxide, at r.t.p., formed.
2FeSO4(s) . Fe2O3(s) + SO2(g) + SO3(g) mass of one mole of FeSO4 = 152 g
number of moles of FeSO4 used , number of moles of Fe2O3 formed,mass of one mole of Fe2O3 , mass of iron(III) oxide formed, number of moles of SO3 formed,volume of sulfur trioxide formed 
4. Copper(II) oxide is formed when copper(II) carbonate is decomposed.
CuCO3 à CO2 + CuO
When Aisha decomposed 10g of copper(II) carbonate he produced 4.7g of copper(II) oxide.
What was his % yield? 
5. Butane is often used as camping gas. 2C4H10(g) + 13O2(g) ® 8CO2(g) + 10H2O(g)
i) What volume of carbon dioxide is produced from combusting 12 000cm3 of butane?
ii) What volume of oxygen is required to combust 8 000cm3 of butane? 
6. Find the concentration of a solution of ethanoic acid given that 25.0 cm3 of the acid reacts with 20.5 cm3 of 1.0 mol/dm3 sodium hydroxide.
CH3COOH(aq) + NaOH(aq) ® CH3COONa(aq) + H2O(l) 
7. A compound contains 40.0 g of carbon, 6.7 g of hydrogen and 53.5 g of oxygen. It has a relative molecular formula of 60.
Find both the empirical and the molecular formula of the compound.