1. 1
   A technician sets up three test tubes, each containing 20 cm3 of dilute hydrochloric acid. A small strip of magnesium is added to the first tube, a small strip of copper to the second, and a small strip of zinc to the third. Bubbles of gas form rapidly around the magnesium, slowly around the zinc, and not at all around the copper. In a separate experiment, a strip of magnesium ribbon is placed into a beaker of blue copper sulfate solution and left for ten minutes.

   (a)

   Which metal reacts most vigorously when a freshly cut strip is added to dilute hydrochloric acid?

   [1 mark]

   • ACopper
   • BMagnesium
   • CSilver
   • DGold

   (b)

   In the second experiment, what colour change would be observed in the copper sulfate solution after the magnesium ribbon has been left in it for ten minutes?

   [1 mark]

   • AThe solution turns from blue to colourless
   • BThe solution turns from colourless to blue
   • CThe solution stays the same shade of blue
   • DThe solution turns from blue to green

   (c)

   Explain, in terms of the transfer of electrons, why magnesium is able to displace copper from copper sulfate solution.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student is comparing two industrial metal extraction processes. In the first, iron oxide ore is heated in a furnace with carbon, producing molten iron and carbon dioxide gas. In the second, purified aluminium oxide is dissolved in molten cryolite and a large electric current is passed through the mixture, producing molten aluminium at the negative electrode and oxygen gas at the positive electrode.

   (a)

   Why is iron extracted from iron oxide by heating the ore with carbon, rather than by electrolysis?

   [1 mark]

   • AIron is more reactive than carbon, so carbon cannot reduce it
   • BIron oxide does not conduct electricity even when molten
   • CIron is less reactive than carbon, so carbon can reduce iron oxide and this is cheaper than electrolysis
   • DElectrolysis only works on non-metal oxides

   (b)

   Why must aluminium be extracted from aluminium oxide by electrolysis instead of by heating with carbon?

   [1 mark]

   • ACarbon reacts explosively with aluminium oxide
   • BAluminium oxide melts at too low a temperature to be heated with carbon
   • CAluminium is less reactive than carbon
   • DAluminium is more reactive than carbon, so carbon cannot displace it from its oxide

   (c)

   Using the terms oxidation and reduction, explain what happens to the iron oxide when it is heated with carbon in the furnace.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A drinks company is deciding between using recycled aluminium and newly extracted aluminium to manufacture its cans. A life cycle assessment is commissioned to compare the environmental impact of the two options, considering every stage from obtaining the raw material through to disposal of the finished can.

   (a)

   Evaluate the advantages of recycling aluminium cans rather than extracting new aluminium from bauxite ore by electrolysis.

   [3 marks]

   (b)

   Describe the stages that would be considered in a life cycle assessment of an aluminium drinks can.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A mining company owns three sites: one containing native gold nuggets, one containing iron ore, and one containing bauxite (aluminium ore). The company is also investigating a fourth site containing a very low-grade copper ore, where the copper concentration is too low for conventional smelting to be economical, and is considering using bacteria or plants to extract the metal instead.

   (a)

   Explain how the reactivity series determines the method used to extract a metal from its ore, using gold, iron and aluminium as examples in your answer.

   [6 marks]

   (b)

   Evaluate the use of biological methods, such as bacterial bioleaching and phytoextraction, for extracting copper from the low-grade ore, compared with conventional smelting.

   [6 marks]

   Total for question 4: 12 marks

End of questions