C10

• Many of the Earth's resources are finite
• Chemists have a role in estimating the amount of reserves remaining and ensuring that the use of resources is sustainable
• Finite resources


  Minerals that have been made through the formation of the world that can be used for human benefit
• Renewable resources


  Resources that can be replenished or regenerated
• Purposes for which humans use the Earth's natural resources


  • Energy and fuels
  • Building materials for shelter
  • Food through farming
  • Fuels for transport
  • Materials for clothing
• The human population is growing very quickly and many people argue that humans are using up the Earth's finite resources at a rate which is too fast and therefore unsustainable
• Chemists try to improve agriculture and industrial processes to provide new products that allow humans to meet their needs in a sustainable way
• Sustainable use of resources means that future generations of humans must also be able to meet their own needs
• Finite resources


  Resources that can only be used once and are in limited supply, e.g. oil
• Earth's crust, oceans and atmosphere


  Finite resources that will one day run out
• Finite resources


  Can be processed to provide energy and useful materials
• Renewable resources


  Resources which will not run out in the foreseeable future, either because the reserves are huge or the current rate of extraction is low
• Crude oil


  One of the most important finite resources in the Earth's crust
• Processing crude oil


  1. Fractional distillation

  2. Cracking
• Sea water


  A renewable resource because there is such a large amount that humans will not use it all up
• Natural products


  Can be supplemented or replaced by agricultural and synthetic products
• Fertilisers


  Until 1910 all were obtained from natural resources such as manure, but the Haber process enabled production from nitrogen in the air
• Synthetic fertilisers have allowed intensive farming to become widespread, which has meant that we can produce enough food to support the growing world population
• There is a clear correlation between the increase in global population and the demand for copper
• The production of copper increased by a factor of ten between 1920 and 1995 (from approximately 1 million tonnes per year to approximately 10 million tonnes per year)
• All humans rely on safe drinking water
• Desalination


  Salt can be removed from sea water to make it safe to drink
• Waste water treatment


  Waste water must be treated before being released into the environment
• Potable water


  Water that is safe for humans to drink
• Potable water is not pure water because it almost always contains dissolved impurities
• Dissolved


  When something is broken up in a liquid and no longer exists
• Salts


  A compound formed by neutralisation of an acid by a base, eg a metal oxide, as the result of hydrogen ions in the acid being replaced by metal ions or other positive ions. Sodium chloride, common salt, is one such compound
• Microbes


  Microscopically small organism, such as a bacterium or single-celled fungus. Also called a microorganism
• Dissolved salts can sometimes be harmful for humans and microbes can cause illnesses
• Potable water in the UK


  • Starting with fresh water is easier than sea water, as removing the large amount of sodium chloride present in sea water requires a lot of energy
• In the UK, rain provides enough fresh water to meet the needs of the population
• Sometimes during the summer months in some areas of the UK, water reserves run low and people are encouraged to conserve tap water by the use of hosepipe bans
• Producing potable water in the UK


  1. Passing the water through filter beds to remove insoluble particles

  2. Sterilising the water to kill microbes
• Insoluble


  Unable to dissolve in a particular solvent. For example, sand is insoluble in water
• Sterilise


  To kill any living organisms, usually microbes that might cause disease, on an object or in a substance
• Potable water


  Water that is safe to drink
• Desalination


  The removal of salt from water. This is an energy-intensive process. Also known as desalinisation.
• It is preferable to make potable water from fresh water reserves rather than from sea water
• Desalination by distillation


  Sea water is heated until it boils. The salt remains in the liquid, and the steam is pure water. The steam is cooled and condensed to make potable water.
• Distillation requires a lot of energy to boil the water, and also to cool the steam down to condense it