Chemistry C3- Alkalis, chlorine and risks

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  • Created by: ameliaG72
  • Created on: 14-05-14 21:49
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  • C3- Chemicals in our lives (Alkalis, Chlorine and Risks)
    • Alkalis
      • Uses of Alkalis: neutralising acid soil, binding dyes to fabrics, converting fats and oils to soap and making glass
      • Alkali's dissolve in water to make solutions with a pH above 7. they react with acids to form salts.
      • Sodium hydroxide+hydrochloric acid= sodium chloride+water
      • Sodium hydroxide+sulfuric Acid= sodium sulfate+water
      • potassium hydroxide+ nitric acid= potassium nitrate+ water
      • Sodium carbonate+hydrochloric acid= sodium chloride+ water+ carbon dioxide
      • A national shortage of alkali lead to scientist inventing new way of making an alkali - raw materials= sodium chloride, limestone and coal. This was the Leblanc process
      • The Leblanc process lead to acidic hydrogen chloride gas being emitted and solid waste which emitted toxic smelly hydrogen sulfide gas
      • 1874- Henry Deacon, worked out how to use pollutant to make chlorine by oxidising hydrogen chloride gas. chlorine can be used as bleach to whiten paper and textiles
    • Chlorination
      • Sewage contaminated water may contain microorganisms that cause cholera and typhoid. Chlorine kills microorganisms.
      • Leads to fewer deaths from water borne diseases
      • Disadvantage of chlorination is that if it reacts with organic matter- trihalomethanes(THMs) may form, this may cause cancer.
    • Brine
      • Chlorine can be made from brine through electroylsis
      • Passes an electric current through the solution, sodium chloride and water react to make new products
      • New Products are: chlorine gas-used to treat water make bleac, plastics and hydrochloric acid, Hydrogen gas- fuel and makes hydrochloric acid, sodium hydroxide solution- used to make soap, paper and bleach
      • Electrolysis needs electricity which needs fossil fuels which causes pollution.
    • Chemical Risks
      • in large quantities synthetic chemicals may harm health, but no evidence in small amounts that there is harms.
      • For many chemicals there is not enough data to make clear judgements
      • 12 banned chemicals because even in tiny amounts: do not break down in the environment, move long distance in air and water and build up in fatty tissues of animals and humans
      • PVC is synthetic chemical, its a polymer- made up of carbon, hydrogen and chlorine.
      • PVC is used to make: window frames, underground water pipes and electric wire insulation and clothing, blood and drip bags for hospitals
      • PVC is softened by plasticisers, these have small molecules which can escape from the plastic and dissolve in liquids- some evidence of infertility and cancer.
      • EU have banned plasticisers in toys and makers say plasticisers have never harmed anyone.
    • Life cycle assessment
      • Analyse the stages of the life of a product includes: uses of resources, energy inputs and outputs and environmental impacts
      • Stages: Making materials- raw materials to make material energy and water processing, manufacturers make the products-materials to make product energy and water in manufacture, people use the product- energy to use product, energy, water and chemicals needed to maintain it, getting rid of the product- energy needed to take it away/ space to store rubbish.

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