5. Using resources

    Cards (26)

    • Earths resources
      • provides warmth , shelter , food and transport
      • Natural resources supplemented by agriculture provide food , timber , clothing and fuels
      • Finite resources from the earth, oceans and atmosphere are processed to provide energy and materials
    • Sustainable development
      • Development that meets the needs of current generations without comprising the ability of the future generations to meet their own needs
      • improves agricultural and industrial processes to provide new products
      • Finite resources —> can be replaced as quickly as they are being used eg. fossil fuels , metals
      • Synthetic —> rubber instead of natural (tree) , synthetic (crude oil)
    • Potable water
      -(Safe to drink) is not pure water as it contains dissolved substances (low levels of dissolved salts + microbes)
      -In the Uk, rain provides water with low levels of dissolved substances ( fresh water) that collects in the ground, lakes and rivers
    • producing potable water
      • choosing an appropriate source of fresh water
      • Passing the water through filter beds
      • Sterilising
      Sterilising agents :
      • chlorine
      • ozone
      • ultraviolet
    • Desalination
      • if supplies of fresh water are limited , desalination of salt water or sea water may be required
      • Desalination can be done by distillation or by processed that use membranes such as reverse osmosis
      • Requires large amounts of energy
    • waste water
      • urban lifestyles and industrial processes produce large amounts of waste water before being released into the environment
      • Sewage + agricultural waste - removal of organic matter and harmful microbes
      • Industrial - removal of organic matter and harmful chemicals
    • waste water treatment
      • screening and grit removal
      • sedimentation to produce sewage sludge + effluent
      • anaerobic digestion of sewage sludge
      • aerobic biological treatment of effluent
    • Obtaining potable water
      • waste water (sewage)
      -many purification steps
      -done in places where water is scarce
      • ground water (aquifers)
      -treated with chlorine
      -can be easily polluted by fertilisers from farms
      -tested carefully
      • salt water
      -required a lot of energy
      -expensive
    • Alternate methods of extracting metals
      • copper ores are becoming scarce
      • new ways of extracting copper from low grade ores
      • avoid traditional mining methods of digging, moving and disposing of large amounts of rocks
    • Alternate methods of extracting metals
      • phytomining
      -uses plants to absorb metal compounds
      -plants are harvested and burned to produce ash that contains metal compounds
      • bioleaching
      -uses bacteria to produce leachate solution that contains metal compounds
      • metal compounds can be processed to obtain the metal
      -eg copper can e obtained from solutions of copper compounds by displacement using scrap iron or electrolysis
    • life cycle assessment
      asses environmental impact of products
      • extracting + processing raw materials
      • Manufacturing and packaging
      • Use and operation during its lifetime
      • Disposal at the end of its useful life , including transport and distribution at each stage
    • LCAs
      • use of water , resources, energy sources and production of some wastes can be fairly Easy quantified
      • Allocating numerical values to pollution effect is less straight forward and require value judgement so LCAs is not purely objective process
      • Selective or abbreviates LCAs can be devised to evaluate a product but these can be misused to reach pre determined conclusions eg in support of claims for advertising purposes
    • paper vs plastic bags
      • paper
      -Timber (renewable)
      -used once
      -recycled , biodegradable , non toxic
      -destroys habitats and waste
      • plastic
      -crude oil (non renewable)
      -reused (eg. Bin liners)
      -recyclable , non biodegradable , can take up landfill space , pollute land
      -crude oil can cause oil leaks

      • both need to be chemically processed and uses a lot of energy
    • Ways of reducing the use of resources
      -metals , glass , building materials , clay ceramics and most plastics are produced from limited raw materials
      -obtaining raw materials from the earth by quarrying and mining causes environmental impacts
      • glass bottles- crushed and melted To make different glass products other products cant be reused so recycled for a different use
      • metals - recycled by melting and recasting or reforming into different products
    • recycling resources
      • amount of separation required for recycling depend on the material and properties required for final product
      • for example , some scrap steel can be added to iron from a blast furnace to reduce the amount of iron that need to be extracted from iron ore
    • corrosion
      • the destruction of materials by chemical reactions with substances in the environment
      test tube 1: Nail in distilled water + open to air
      test tube 2: nail in distilled water (boiled) covered in oil (no air)
      test tube 3 : nail in anhydrous calcium chloride powder + bung + no water

      results
      test tube 1 : nail rust
      test tube 2 + 3 : nail doesn’t rust
      therefore rusting required air and water
    • prevention of corrosion
      • applying A coating that accts as a barrier eg greasing , painting or electroplating
      Eg. Alumiuminum has an oxide coating that protects metal corrosion
      • some coatings are reactive and contain a more reactive metal to provide sacrificial protection
      Eg. zinc used to galvanise iron
    • Alloys as useful metals
      • bronze - copper + tin (statues)
      • Brass - copper + zinc ( door handles and musical instruments)
      • Gold - silver , copper + zinc (jewellery)
      -24 carats 100% pure cold , 18 carat = 75% gold
      • steel - specific amounts of carbon and other metals
      -high carbon steel - strong but brittle (cutting tools eg chisels)
      -low carbon steels- softer and more easily shaped (car bodies)
      Steels containing chromium and nickel (stainless steel) are hard and resistant to corrosion
      Aluminium alloys are low desnity
    • Ceramic and composites
      • Soda lime glass —> heating mixture of sand + sodium carbonate + limestone
      • Borosilicate glass —> sand + boron trioxide , melts at higher temperatures
      • clay ceramics (pottery + bricks) —> shaping wet clay , heat in furnace
    • ceramics and composites
      Most composites are made of two materials:
      • matrix or binder surrounding and binding together fibres
      • Reinforcements - Fragments of the other materials
      Eg.
      Fibre glass - low density and strong
      Carbon fibre - strong and light
      Wood
    • polymers
      • thermosoftening polymers
      -melt when heated
      -chains connected by intermolecular forces
      • thermosetting polymers
      -do not melt when heated
      -chains connected by strong cross links
      • both produced from ethene
    • The Haber process
      -Used to manufacture ammonia which produces nitrogen based fertilisers
      -Nitrogen + hydrogen \leftrightarrowammonia
      -Raw materials
      • nitrogen (air)
      • Hydrogen (reacting methane and steam)
      Purified gases are passed over:
      • iron catalyst
      • High temperature 450
      • high pressure 200 at pushers
      On cooling, ammonia liquifies and is removed
      Remaining hydrogen and nitrogen is recyled
    • production of NPK fertilisers
      NPK ( nitrogen , phosphorus , potassium ) fertilisers improves agricultural productivity.
      • Using a variety of raw materials in several integrated processes.
      • formulation of various salts obtaining appropriate percentages of the elements
      • Ammonia can be used to manufacture ammonium salts and nitric acid
    • uses of NPK fertilisers
      • potassium chloride , potassium sulfate and phosphate rock are obtained by mining but phosphate rock cant be used directly as fertilisers
      • phosphate rock is treated with nitric acid of sulfuric acid to produce soluble salt that can be used as fertilisers
    • phosphate rock reactions
      • phosphate rock + nitric acid —> phosphoric acid + calcium nitrate
      • Phosphorus neutralised by ammonia —> ammonium phosphate (NPK)
      • phosphate rock + sulfuric acid —> calcium phosphate + calcium surface (single super phosphate) (NPK)
      • Phosphoric acid + phosphate rocks —> triple super phosphate (NPK)
    • industrial vs lab production
      • school lab
      -dilute solutions (safe)
      -small amounts (batch process)
      • industry
      -gas and more concentrated
      -continuous process
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