1. 1
   An aluminium recycling plant explains to visitors that extracting new aluminium metal from its ore is far more energy-intensive and expensive than melting down and reusing scrap aluminium, and asks them to consider why this might be the case.

   (a)

   Which method is used to extract aluminium metal from its ore?

   [1 mark]

   • AElectrolysis of molten aluminium oxide
   • BHeating the ore with carbon in a blast furnace
   • CSimply melting the ore, since aluminium occurs naturally as the pure element
   • DReacting the ore with dilute hydrochloric acid

   (b)

   Which statement correctly explains why this particular extraction method must be used for aluminium, rather than the cheaper method used for extracting iron?

   [1 mark]

   • AAluminium ore does not conduct electricity, so electrolysis is the only option available
   • BAluminium is less reactive than carbon, so carbon would react too violently with the ore
   • CAluminium is more reactive than carbon, so carbon cannot displace it from its ore; only electrolysis can supply enough energy to separate the ions
   • DAluminium melts at a lower temperature than iron, so electrolysis is simply more convenient

   (c)

   Explain why recycling aluminium (by melting down scrap metal) uses far less energy than extracting new aluminium from its ore.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An architect is choosing which type of steel to use for the frame of a new building constructed near the coast, where salty sea air is known to cause ordinary steel to rust quickly, while also considering steel for a separate section of railway track further inland.

   (a)

   An architect is choosing steel for the frame of a new building constructed near the coast, where salty sea air causes ordinary steel to rust quickly. Which type of steel would be the most suitable choice to resist this corrosion?

   [1 mark]

   • APure iron
   • BLow-carbon steel
   • CHigh-carbon steel
   • DStainless steel

   (b)

   For a section of railway track further inland, the architect instead recommends high-carbon steel rather than low-carbon steel. Which property of high-carbon steel makes it more suitable for railway track, which must withstand heavy repeated loads without deforming?

   [1 mark]

   • AHigh-carbon steel is softer and more easily bent into shape than low-carbon steel
   • BHigh-carbon steel is harder and stronger than low-carbon steel, though more brittle
   • CHigh-carbon steel conducts electricity much better than low-carbon steel
   • DHigh-carbon steel does not contain any iron, unlike low-carbon steel

   (c)

   Explain, in terms of composition, why stainless steel resists rusting far better than low-carbon steel, and why steel of any kind is described as an alloy.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A mining company extracts copper from two different sources: one deposit contains small nuggets of pure, uncombined copper metal, while a second, larger deposit contains copper only in the form of copper ore, where copper compounds are mixed in with rock.

   (a)

   Explain why copper can sometimes be found as the pure element, and describe, in general terms, why a chemical extraction process is needed for the ore but not for the native copper.

   [3 marks]

   (b)

   The mining company's chemist proposes heating the copper ore with carbon to extract the copper. Comment on whether this method is likely to be suitable, given copper's position in the reactivity series relative to carbon.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A metals company produces both iron and aluminium on an industrial scale using different extraction methods, and is training new staff to understand why each metal requires its own particular extraction process.

   (a)

   Describe how iron is extracted from its ore and how aluminium is extracted from its ore, and explain, using the reactivity series, why two different methods are needed.

   [6 marks]

   (b)

   The company also manufactures alloys from both metals, such as steel from iron and duralumin from aluminium, for use in products that need to be harder than the pure metal alone. Explain, in terms of structure and bonding, why alloys are generally harder than the pure metals they are made from.

   [6 marks]

   Total for question 4: 12 marks

End of questions