water

• Natural resources are all around us and provide us with the materials we need for shelter, food, warmth and transport
• Natural resources


  • Living: plants and animals
  • Non-living: Minerals, fossil fuels, water and air
• Some resources can be replaced by synthetic products and others cannot
• Two examples of sustainable processes

  • Rubber
  • Fertilisers
• Plants are natural resources that provide materials for food, shelter and clothing
• Renewable resources


  Resources which can be replenished or replaced in a finite time in a human timescale
• Example of renewable resource

  • Timber
• Finite/Non-renewable resources


  Resources that don't reform quickly enough or don't reform at all
• Examples of finite/non-renewable resources

  • Minerals from the Earth's crust
  • Metal ores
• After extraction, many resources require further processing to make the desired products. These processes require energy and make the extraction process less sustainable
• Examples of less sustainable processes

  • Reduction of metals from ores
  • Fractional distillation of crude oil
• The extraction of non-renewable resources carries risks. The Earth's natural resources are being depleted and large amounts of energy are being consumed in the process of extraction
• Building materials such as limestone can often be non-renewable, but recycling and re-using materials ensure that buildings of the future are constructed in a sustainable way and reduce the need to further exploit finite mineral resources
• Non-renewable resources are the same as finite resources and both terms are interchangeable
• Potable water


  Water that has been processed and is safe for human consumption and daily use
• The difference between pure water and potable water is that pure water is solely made up of H2O molecules, whereas potable water may contain different substances, usually dissolved minerals and salts
• Characteristics of potable water

  • pH between 6.5 and 8.5
  • Dissolved substances (e.g. salts) present in very small regulated quantities
  • Free of bacteria or potentially harmful microbes
• Fresh water


  Water that is relatively free from dissolved substances e.g. rainwater
• Surface water


  Water that collects in reservoirs, lakes and rivers
• Groundwater


  Water that collects in aquifers, which are porous rocks that store water underground
• Process to obtain potable water

  1. Choose a suitable fresh water source

  2. Filtration to remove debris

  3. Sterilisation to remove dangerous bacteria or microbes
• Desalination


  The treatment of seawater to remove the salt by distillation or reverse osmosis
• Desalination is an expensive process as it consumes large amounts of energy and is not ideal when producing large quantities of fresh water
• The way in which potable water is prepared and delivered to a population depends largely on the local conditions of geology
• Required Practical 8(a): Analysing and Purifying Water and making it Safe to Drink


  1. Use universal indicator paper to determine pH

  2. Accurately weigh an empty evaporating basin

  3. Add 25 cm3 of water sample

  4. Heat the evaporating basin until solids start to form and majority of water has evaporated

  5. Leave for remaining water to evaporate off

  6. Weigh the cooled evaporating basin again and calculate the mass of the dissolved solids
• The results could be compared to the national water safety levels and by analysis the regions of each sample could be deducted e.g. region of high acid rain, water from a salt water supply etc.
• Make sure you know the names of common laboratory equipment and can draw and label apparatus used in the required practicals
• Required Practical 8(b): To Purify a Water Sample by Distillation


  1. Set up a simple distillation apparatus with a conical flask, delivery tube, boiling tube and ice bath

  2. Heat the water sample to separate the pure water from the unwanted substances
• Required Practical 8(b): To Purify a Water Sample by Distillation


  1. Add water sample to conical flask

  2. Heat water until boiling

  3. Reduce heat to gentle boil

  4. Collect distilled water

  5. Analyse distilled water
• Materials


  • 10 cm3 of water sample A
  • Bunsen burner
  • Tripod
  • Gauze
  • Heatproof mat
  • Clamp and clamp stand
  • Conical flask with delivery tube and bung
  • Boiling tube
  • Ice bath
• Waste Water


  Water used on a daily basis in a domestic environment, e.g. washing-up dishes, showers, baths, cooking
• Sewage


  Domestic and agricultural waste that needs to be processed to remove organic matter, harmful microbes, particulates and toxins
• If waste water is not treated, it could potentially pose health risks for the population
• Waste water produced by the Haber process and other industrial processes needs to be gathered and treated appropriately as it contains harmful chemicals and organic matter
• Sewage Treatment


  1. Screening & Grit Removal

  2. Sedimentation

  3. Aerobic Digestion

  4. Anaerobic Digestion
• When there are toxic substances within waste water, it is important to use additional phases of treatment such as using membranes, adding additional chemicals, and using UV radiation
• Sewage water is often treated in areas where there is little freshwater available, as it uses less energy than the desalination of salt water
• Biological Methods


  Phytoextraction and bioleaching are two relatively new methods of extracting metals that rely on biological processes
• Biological methods are very slow and also require either displacement or electrolysis to purify the extracted metal
• Biological methods are used to extract metals from mining wastes, which may contain small quantities of metals or toxic metals that need to be removed from that environment