Extraction of metals and corrosionIB MYP Chemistry: Subtopic test

1. 1
   A steelworks in Jamshedpur, India, makes iron in a blast furnace. The furnace is charged with iron ore (mainly haematite, iron(III) oxide, Fe₂O₃), coke (carbon), limestone and hot air.

   (a)

   Why can iron be extracted from its ore by heating with carbon?

   [1 mark]

   • AIron is more reactive than carbon
   • BIron is less reactive than carbon
   • CCarbon acts as a catalyst for the extraction
   • DIron is above aluminium in the reactivity series

   (b)

   In the blast furnace, iron(III) oxide is changed into iron. Which statement describes this change?

   [1 mark]

   • AOxidation, because the oxide gains oxygen
   • BOxidation, because the oxide loses oxygen
   • CReduction, because the oxide loses oxygen
   • DReduction, because the oxide gains oxygen

   (c)

   Write a balanced symbol equation for the reduction of iron(III) oxide by carbon monoxide.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student set up three test tubes, each containing a clean iron nail, and left them for one week. Tube 1: the nail was in water that had been boiled to remove dissolved air, with a layer of oil poured on top. Tube 2: the nail was in a stoppered tube with a drying agent (anhydrous calcium chloride) at the bottom, so the air was dry. Tube 3: the nail was half-covered with ordinary tap water and left open to the air. Only the nail in Tube 3 had rusted.

   (a)

   What is the purpose of the layer of oil in Tube 1?

   [1 mark]

   • ATo stop air dissolving into the boiled water
   • BTo supply oxygen to the nail
   • CTo help the water boil more easily
   • DTo speed up the rusting of the nail

   (b)

   Which conclusion about rusting is best supported by the three tubes?

   [1 mark]

   • AIron rusts in water alone
   • BIron rusts in oxygen alone
   • CIron rusts only when a drying agent is present
   • DIron needs both water and oxygen to rust

   (c)

   Identify the independent variable and the dependent variable in this investigation.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   At a smelter in Iceland, aluminium is extracted from bauxite, which is purified to give aluminium oxide, Al₂O₃. Iceland's geothermal power stations provide cheap electricity. The aluminium oxide is mixed with molten cryolite in a large steel tank lined with graphite, and a direct current is passed through the mixture.

   (a)

   Explain why the aluminium oxide is dissolved in molten cryolite for electrolysis instead of being melted on its own.

   [3 marks]

   (b)

   Explain why aluminium has to be extracted by electrolysis and not by heating its oxide with carbon, and describe what is formed at each electrode.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The government of a West African country is deciding whether to allow a company to open a large open-cast bauxite mine on forested land. The mine would create jobs and bring export income. The company also says it could instead build a plant to recycle aluminium drinks cans collected in nearby cities.

   (a)

   Discuss the benefits and drawbacks of opening the bauxite mine.

   [6 marks]

   (b)

   Evaluate the company's plan to recycle aluminium cans instead of mining new bauxite.

   [6 marks]

   Total for question 4: 12 marks

End of questions