1. 1
   A student places a coil of magnesium ribbon into blue aqueous copper(II) sulfate solution. After a few minutes a pink-brown coating forms on the magnesium and the blue colour of the solution fades. The student repeats the experiment using an iron nail in the same solution and observes a similar, but slower, colour change and coating.

   (a)

   What is the name of the type of reaction taking place between the magnesium and the copper(II) sulfate solution?

   [1 mark]

   • ADisplacement
   • BNeutralisation
   • CElectrolysis
   • DThermal decomposition

   (b)

   Which observation from the experiment shows that magnesium is more reactive than iron?

   [1 mark]

   • ABoth metals form the coating at exactly the same rate
   • BThe magnesium reacts faster and produces its coating more quickly than the iron
   • CIron never displaces copper because copper is more reactive than iron
   • DThe blue colour is unaffected when iron is used

   (c)

   Explain, in terms of the reactivity series, why both magnesium and iron can displace copper from copper(II) sulfate solution, but copper cannot displace magnesium or iron from their salt solutions.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An artist is selecting a metal wire to weave into a large outdoor sculpture. She needs a metal that can be bent into curves and hammered into thin sheets without cracking, and that will also conduct heat away quickly if warmed by sunlight.

   (a)

   Which pair of properties allows a metal to be hammered into sheets and drawn into wires without breaking?

   [1 mark]

   • ABrittle and ductile
   • BMalleable and a poor conductor of heat
   • CMalleable and ductile
   • DBrittle and a poor conductor of heat

   (b)

   The sculpture will stand outdoors in direct sunlight. Which property should the artist consider if she wants the sunlit side of the sculpture not to feel much hotter than the shaded side?

   [1 mark]

   • ALow electrical conductivity
   • BLow density
   • CHigh melting point
   • DHigh thermal conductivity

   (c)

   State two physical properties, other than malleability and ductility, that are typical of metals and that the artist could also expect this wire to show.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A national mint is redesigning a coin and decides to make it from cupronickel, an alloy of copper and nickel, instead of pure copper. The coins need to withstand years of handling in tills and pockets without wearing down or denting.

   (a)

   Define what is meant by an alloy, and explain in terms of structure why cupronickel is harder than pure copper.

   [3 marks]

   (b)

   Stainless steel, an alloy of iron with chromium, nickel and carbon, is often used to manufacture surgical instruments instead of pure iron. Suggest, with reasons, why stainless steel is a more suitable material than pure iron for this application, and explain in terms of structure why the alloy is harder than pure iron.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A council parks department wants to stop the steel support poles of children's playground equipment from rusting at ground level, where they are frequently damp. A technician tests the effect of connecting a steel nail to a strip of a different metal (magnesium, zinc, tin or copper in separate trials) by wire, then leaving each connected pair in damp soil for two weeks. The nails connected to magnesium and zinc show no rusting, the nail connected to tin rusts more than an unconnected control nail, and the nail connected to copper rusts fastest of all.

   (a)

   Using the reactivity series, explain the pattern of results: why the nails connected to magnesium and zinc did not rust, while the nail connected to copper rusted fastest.

   [6 marks]

   (b)

   The council decides to protect the real playground poles by bolting zinc collars around the base of each pole, and replacing the collars every few years. Explain what conditions are needed for iron to rust, and explain, in terms of electron transfer, why attaching zinc collars prevents the steel poles from rusting even though the zinc itself gradually corrodes away.

   [6 marks]

   Total for question 4: 12 marks

5. 5
   A regional mining and metals company is comparing the cost of processing three ores it has rights to: haematite (iron oxide), bauxite (aluminium oxide) and galena (lead sulfide). Managers want to know why haematite can be processed cheaply by heating with carbon in a blast furnace, while bauxite needs the far more expensive process of electrolysis.

   (a)

   Which statement correctly explains why iron can be extracted from haematite by heating with carbon, but aluminium cannot be extracted from bauxite in the same way?

   [1 mark]

   • AIron is less reactive than carbon, so carbon can reduce it from its oxide, but aluminium is more reactive than carbon, so carbon cannot reduce it
   • BIron is more reactive than carbon, so carbon reduces it, while aluminium is less reactive than carbon
   • CAluminium oxide does not contain oxygen, so it cannot be reduced by carbon
   • DIron ore is a liquid at room temperature, making it easier to heat than solid bauxite

   (b)

   Because carbon cannot reduce aluminium oxide, aluminium is instead extracted by electrolysis of molten aluminium oxide. Why must the aluminium oxide be molten (or dissolved) rather than solid for this process to work?

   [1 mark]

   • ASolid aluminium oxide reacts explosively with carbon electrodes
   • BThe ions in solid aluminium oxide are fixed in place and cannot move to carry an electric current, but in the molten state the ions are free to move to the electrodes
   • CSolid aluminium oxide is a good conductor of electricity, so melting it is unnecessary but done for convenience
   • DMelting removes the aluminium ions completely, leaving only oxide ions to be electrolysed

   (c)

   State the main ore of aluminium, and explain why the extraction of aluminium by electrolysis is more expensive than the extraction of iron by reduction with carbon.

   [2 marks]

   Total for question 5: 4 marks

6. 6
   A telecoms company is planning a new network. For the core wiring inside buildings it chooses copper wire, and for the long-distance overhead cables strung between pylons across open countryside it chooses aluminium cable reinforced with a steel core.

   (a)

   Which property makes copper a suitable choice for the core wiring inside buildings?

   [1 mark]

   • ACopper is the least dense of all common metals
   • BCopper reacts readily with oxygen to form a protective layer
   • CCopper is an excellent conductor of electricity and can be drawn into thin, flexible wires
   • DCopper has a very low melting point, making it easy to cut

   (b)

   Why is aluminium, rather than copper, used for the very long overhead cables strung between pylons, even though copper is a slightly better conductor of electricity?

   [1 mark]

   • AAluminium is a better conductor of electricity than copper
   • BAluminium is much cheaper to mine because it is more reactive than copper
   • CAluminium does not conduct electricity at all, so it is safer for overhead use
   • DAluminium has a much lower density than copper, so long cables are lighter and put less strain on the pylons

   (c)

   The aluminium overhead cable has a steel core running through its centre. Suggest why a steel core, rather than solid aluminium, is used to give the cable strength.

   [2 marks]

   Total for question 6: 4 marks

7. 7
   An allotment committee inspects the steel roof frame of a communal garden shed built eight years ago. Sections that were regularly repainted show almost no damage, but a corner where the paint cracked and peeled two years ago is now covered in a flaky orange-brown layer and has become noticeably thinner.

   (a)

   Name the substance that has formed on the unpainted corner of the roof frame, state the two conditions needed for it to form, and explain why the painted sections have not been affected.

   [3 marks]

   (b)

   The committee is deciding how to protect a new steel-framed shed on a similarly exposed site. One option is regular painting; another is galvanising, coating the steel with a thin layer of zinc. Explain, in terms of the reactivity series, why galvanising gives better long-term protection than painting alone, even if the zinc coating becomes scratched.

   [4 marks]

   Total for question 7: 7 marks

8. 8
   A sports equipment company is designing a new tennis racket frame. They are choosing between a pure aluminium frame and a frame made from an aluminium alloy containing small amounts of magnesium and other metals.

   (a)

   Explain, in terms of structure, why the aluminium alloy frame is likely to be stronger and more resistant to bending than a frame made of pure aluminium, and explain why using an alloy rather than pure aluminium allows the company to make a lighter racket frame for the same strength.

   [6 marks]

   (b)

   The company also produces a cheaper training racket using plain low-carbon steel rather than the aluminium alloy. Explain, referring to relevant physical properties, why the steel racket is heavier than the alloy racket, and suggest one further property of aluminium (other than its strength as an alloy) that also makes it a good choice of material for sports equipment.

   [6 marks]

   Total for question 8: 12 marks

End of questions