1. 1
   A student reacts a known mass of magnesium with excess hydrochloric acid and calculates that exactly 0.1 mol of hydrogen gas is produced, according to the reaction Mg + 2HCl -> MgCl2 + H2.

   (a)

   A student reacts magnesium with excess hydrochloric acid and calculates that 0.1 mol of hydrogen gas is produced. What is the assumed molar gas volume of any gas at room temperature and pressure?

   [1 mark]

   • A24 dm3
   • B22.4 dm3
   • C1 dm3
   • D100 dm3

   (b)

   Which equation should the student use to calculate the volume of hydrogen gas produced, given the number of moles?

   [1 mark]

   • AVolume = number of moles x 24 dm3
   • BVolume = number of moles / 24 dm3
   • CVolume = 24 dm3 / number of moles
   • DVolume = number of moles + 24 dm3

   (c)

   Calculate the volume of hydrogen gas, in dm3, produced in this reaction, showing your working.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A chemist collects 6000 cm3 of carbon dioxide gas produced from the thermal decomposition of limestone in a lime kiln, and wants to calculate how many moles of gas this volume represents.

   (a)

   A chemist collects 6000 cm3 of carbon dioxide gas from a lime kiln reaction and wants to calculate how many moles of gas this represents. What is 6000 cm3 expressed in dm3?

   [1 mark]

   • A6 dm3
   • B0.6 dm3
   • C60 dm3
   • D600 dm3

   (b)

   Which rearrangement of V = n x 24 should the chemist use to calculate the number of moles of gas from a known volume?

   [1 mark]

   • An = V / 24
   • Bn = V x 24
   • Cn = 24 / V
   • Dn = V + 24

   (c)

   Calculate the number of moles of carbon dioxide gas collected, showing your working.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student reacts 5.0 g of calcium carbonate, CaCO3 (Mr = 100), completely with excess dilute hydrochloric acid, according to the equation CaCO3 + 2HCl -> CaCl2 + H2O + CO2, and wants to predict the volume of carbon dioxide gas that will be produced.

   (a)

   Calculate the number of moles of calcium carbonate used, and hence the number of moles of carbon dioxide gas produced, showing your working.

   [3 marks]

   (b)

   Using your answer to part (a), calculate the volume of carbon dioxide gas produced, giving your final answer in cm3, and showing your working.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An industrial chemist is planning production for a chemical plant. One task involves the Haber process (N2 + 3H2 -> 2NH3), where 6.0 g of hydrogen gas reacts completely with excess nitrogen. Another task requires calculating the mass of magnesium needed to produce a specific volume of hydrogen gas by reacting it with excess hydrochloric acid (Mg + 2HCl -> MgCl2 + H2), where 3.6 dm3 of hydrogen gas is required.

   (a)

   An industrial chemist is planning the Haber process, in which nitrogen reacts with hydrogen according to the equation N2 + 3H2 -> 2NH3. In one calculation, 6.0 g of hydrogen gas, H2 (Mr = 2), reacts completely with excess nitrogen. Calculate the volume, in dm3, of ammonia gas produced at room temperature and pressure, showing full working.

   [6 marks]

   (b)

   The chemist also needs to calculate the mass of magnesium, Mg (Ar = 24), required to produce exactly 3.6 dm3 of hydrogen gas at room temperature and pressure, by reacting it with excess hydrochloric acid, according to the equation Mg + 2HCl -> MgCl2 + H2. Calculate this mass, showing full working.

   [6 marks]

   Total for question 4: 12 marks

End of questions