2021

• Explain why there is an attraction between a C=C double bond and Br2.

  C=C double bond has high electron density

  Br-Br becomes polarised

  Slightly positive Br attracted to C=C
• Figure 2 shows the apparatus set up by a student to make propanone by this method.

  There are three problems with the apparatus set up in Figure 2.

  For each problem:

  • identify
  • describe issue
  • suggest how solved

  ANTI-BUMPING GRANULES

  • no anti-bumping granules
  • to prevent large bubbles
  • add some

  OPEN SYSTEM + NO THERMOMETER

  • system should be closed to prevent gases escaping
  • close with bung and thermometer
  • to allow collection of propanone only

  WATER DIRECTION IN CONDENSER

  • water flows in wrong direction through condenser
  • not cool enough
  • product may not condense
• State the benefit to life on Earth of ozone in the upper atmosphere.

  Absorbs harmful UV radiation
• Suggest one reason why the use of CFCs was not restricted until several years after Rowland and Molina published their research.

  Lack of alternatives to CFCs

  Lack of evidence that ozone was being depleted
• CFC-11 is a greenhouse gas that can contribute to global warming. State and explain how CFC-11 is able to contribute to global warming.

  Absorbs infrared radiation

  Molecule has polar bonds
• This question is about poly(propene).

  Crude oil -> naphtha -> propene -> poly(propene)

  For each step, name the process and state briefly the purpose of the process that leads to the formation of poly(propene).

  FRACTIONAL DISTILLATION

  Separated into mixtures of compounds with similar boiling points

  THERMAL CRACKING

  To make alkenes/ shorter molecules

  ADDITION POLYMERISATION

  Molecules joined together to produce long chain molecule
• Poly(propene) is not biodegradable because it is unreactive. Explain why poly(propene) is unreactive.

  No polar bonds
• Scientists are developing new polymers, including some that are biodegradable. Suggest why it is beneficial for some polymers to be biodegradable.

  Prevents build-up of waste in landfill
• Referring to the reaction of 1-bromopropane with a solution of potassium cyanide in aqueous ethanol. What is the organic product of this reaction?

  A propylamine

  B butylamine

  C propanenitrile

  D butanenitrile

  D
• Which statement is not correct about the industrial production of ethanol from ethene at 300 °C?

  C2H4(g) + H2O(g) ⇌ C2H5OH(g) ΔH = −46 kJmol–1

  A The reaction is catalysed by an acid.

  B The reaction has 100% atom economy.

  C An increase in temperature decreases the equilibrium yield of ethanol.

  D An increase in pressure increases the value of Kc

  D
• Which statement is not correct about the pollutant sulfur dioxide?

  A It can be removed from car exhaust gases by a catalytic converter.

  B It can be removed from power station flue gases by reaction with calcium oxide.

  C It can cause respiratory problems.

  D It can cause acid rain.

  A