topic 10

• What is sustainable development?


  Development that meets current needs without compromising future
• What are the steps to produce potable water in the UK?

  • Choose an appropriate source of fresh water
  • Pass through filter beds to remove solids
  • Sterilize to kill microbes
• What are the sterilising agents for potable water?

  Chlorine, ozone, or ultraviolet light
• Why must the amount of chlorine added to water be monitored?

  Because chlorine is a toxic gas
• What is the advantage of using ultraviolet light for sterilization?

  Avoids adding chemicals to the water
• How is desalination carried out?

  By distillation or reverse osmosis
• What is reverse osmosis?

  Sea water is pushed through a membrane
• What is required to push water through the reverse osmosis membrane?

  High pressure is needed
• How is wastewater produced and treated?

  • Produced by urban lifestyles and industrial processes
  • Requires treatment before environmental release
  • Sewage needs removal of organic matter and microbes
  • Industrial wastewater needs removal of harmful chemicals
• What do new mining methods avoid compared to traditional methods?

  Avoid digging and disposing large rock amounts
• What is phytomining?

  Using plants to absorb metal compounds
• What is bioleaching?

  Using bacteria to produce leachate solutions
• What is the main advantage of phytomining and bioleaching?

  They need less energy than traditional methods
• What is the main disadvantage of phytomining and bioleaching?

  They are slow to carry out
• What are the stages of Life Cycle Assessments (LCAs)?

  1. Extracting and processing raw materials
  2. Manufacturing and packaging
  3. Use and operation during its lifetime
  4. Disposal at the end of its useful life
• How do we reduce the use of resources?

  By reducing, reusing, and recycling materials
• What are the advantages of recycling?

  • Less acid rain and pollution
  • Metal ore reserves last longer
  • Conserved energy for extraction
  • Less mining and landfill
  • Creates local employment
• What are the disadvantages of recycling?

  • Collection and transport problems
  • Cost of transport issues
  • Difficulty separating metals from appliances
• What is corrosion?

  Destruction of materials by chemical reactions
• How can corrosion be prevented?

  By applying a barrier coating
• What is sacrificial protection?

  Using a more reactive metal to corrode first
• What is bronze made of?

  An alloy of copper and tin
• What is brass made of?

  An alloy of copper and zinc
• How is the purity of gold measured?

  In carats, with pure gold as 24 carat
• What are aluminium-magnesium alloys used for?

  Used in aerospace manufacturing
• What are the properties of high carbon steel?

  Strong but brittle
• What are the properties of low carbon steel?

  Softer and more easily shaped
• What are stainless steels made of?

  Iron with chromium and nickel
• How are the properties of polymers determined?

  By the monomers and production conditions
• What are the structures of thermosoftening and thermosetting polymers?

  • Thermosetting: Do not melt, linked by strong cross-links
  • Thermosoftening: Soften on heating, can be remoulded
• How is soda-lime glass made?

  By heating sand, sodium carbonate, and limestone
• How are clay ceramics made?

  By shaping wet clay and heating in a furnace
• How are composites formed?

  • Fibres or fragments of one material (reinforcement)
  • Surrounded by a binder/matrix material
• What are the key stages of the Haber process?

  1. Purified H2 and N2 over Fe catalyst
  2. High temperature (450 °C) and pressure (200 atm)
  3. Ammonia formation: N2 + 3 H2 ⇌ 2 NH3
  4. Ammonia liquefies and is removed
  5. Remaining gases are recycled
• Why is the temperature in the Haber process a compromise?

  Lower temperature gives higher yield but slower rate
• Why is the pressure in the Haber process a compromise?

  Higher pressure increases yield but is costly
• How are nitrogen, phosphorus, and potassium used?

  As fertilisers to improve agricultural productivity
• How is industrial production of NPK fertilisers achieved?

  By reacting ammonia with requisite acids
• How is phosphate rock utilized in fertiliser production?

  Reacted with acids to produce phosphoric acid
• What are the processes involved in sewage treatment?

  1. Screening and grit removal
  2. Sedimentation to produce sludge and effluent
  3. Anaerobic digestion of sewage sludge
  4. Aerobic biological treatment of effluent