1. 1
   An oil refinery separates crude oil into fractions by fractional distillation, then supplies each fraction to a different customer according to its properties.

   (a)

   Which fraction is collected nearest the top of the fractionating column?

   [1 mark]

   • ARefinery gas
   • BDiesel oil
   • CFuel oil
   • DBitumen

   (b)

   A customer requests the fraction used as chemical feedstock for making plastics and other organic chemicals. Which fraction does the refinery supply?

   [1 mark]

   • AKerosene
   • BNaphtha
   • CBitumen
   • DLubricating oil

   (c)

   Describe how the properties of the fractions change from the bottom to the top of the fractionating column.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A power station burns natural gas, which is mostly methane, in a well-ventilated furnace with a plentiful supply of air. Environmental monitors nearby record the effect of the flue gases on nearby vegetation and buildings.

   (a)

   Which two products form from this complete combustion?

   [1 mark]

   • ACarbon and hydrogen
   • BCarbon monoxide and water
   • CCarbon dioxide and water
   • DCarbon monoxide and hydrogen

   (b)

   The environmental monitors detect a haze of fine particulates and traces of carbon monoxide near a different part of the plant, where the fuel is burned with a restricted air supply. What has most likely caused these pollutants?

   [1 mark]

   • AComplete combustion of the fuel
   • BCracking of the fuel
   • CFractional distillation of the fuel
   • DIncomplete combustion of the fuel

   (c)

   The monitors also detect sulfur dioxide near the plant, released from impurities in the fuel. State the source of the sulfur dioxide and describe its adverse effect on the surrounding environment.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   In the early days of the petroleum industry, engineers noticed that heavier fractions of crude oil, such as fuel oil, were in far greater supply than lighter fractions such as gasoline, even though demand for gasoline was much higher. They later solved this by heating the heavier fractions to high temperatures in the presence of a catalyst.

   (a)

   Name this process, state the conditions it uses, and state the general type of hydrocarbon it converts larger alkane molecules into.

   [3 marks]

   (b)

   Explain why the engineers needed to carry out this process rather than simply relying on fractional distillation alone, and describe why the products formed are more economically useful than the original heavier fraction.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A household is deciding whether to heat its water using a natural gas boiler or an electric immersion heater supplied by a coal-fired power station.

   (a)

   Discuss the environmental impact of burning natural gas directly in the home compared with burning coal to generate the electricity, referring to the pollutants produced by each fuel and their effects.

   [6 marks]

   (b)

   The household is also considering switching entirely to renewable electricity in the future. Explain, using your knowledge of fossil fuel combustion and its environmental effects, why increasing the use of renewable energy and hydrogen is suggested as a strategy to reduce climate change.

   [6 marks]

   Total for question 4: 12 marks

End of questions