Polymers and crackingIB MYP Chemistry: Subtopic test

1. 1
   An oil refinery in Rotterdam separates crude oil into fractions. It produces more long-chain hydrocarbons than customers need, and too few shorter molecules for petrol and for making plastics. To fix this, it heats the long-chain hydrocarbons so that they break into smaller molecules.

   (a)

   What is the name of the process that breaks long-chain hydrocarbons into smaller molecules?

   [1 mark]

   • AFractional distillation
   • BCracking
   • CPolymerisation
   • DCombustion

   (b)

   Decane, C₁₀H₂₂, is cracked to make octane, C₈H₁₈, and one other product. What is the other product?

   [1 mark]

   • AC₂H₆
   • BC₂H₂
   • CCH₄
   • DC₂H₄

   (c)

   State two conditions used for cracking.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student is shown a sample of poly(ethene) and is told that it is made from ethene, C₂H₄.

   (a)

   What is the name for the small molecules, such as ethene, that join together to make a polymer?

   [1 mark]

   • AIsomers
   • BFractions
   • CMonomers
   • DPolymers

   (b)

   Why can ethene molecules join together to make poly(ethene)?

   [1 mark]

   • AEach molecule has a C=C double bond that can open
   • BEach molecule contains only C-C single bonds
   • CEach molecule contains an -OH group
   • DEach molecule is a long-chain alkane

   (c)

   Describe what happens to the ethene molecules during addition polymerisation.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Propene, C₃H₆, is another alkene. Poly(propene) is used to make rope, food containers and school chairs.

   (a)

   Name the monomer and the polymer in this process, and explain why it is called addition polymerisation.

   [3 marks]

   (b)

   Explain how cracking provides propene, and why a long-chain alkane cannot be used to make a polymer by addition polymerisation.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A coastal town council is considering banning thin poly(ethene) carrier bags in its shops. Poly(ethene) is made from ethene, which comes from long-chain alkanes obtained from crude oil. The council wants shoppers to use paper bags or reusable bags instead.

   (a)

   Design an investigation to compare how quickly a poly(ethene) bag and a paper bag break down when buried in soil.

   [6 marks]

   (b)

   Discuss and evaluate the council's proposal to ban thin poly(ethene) carrier bags.

   [6 marks]

   Total for question 4: 12 marks

End of questions