Core Chemistry - Topic 3 Acids

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  • Created by: Katie
  • Created on: 09-04-13 19:26

Indigestion

  • Indigestion - stomach producing too much acid
  • Heartburn - acid escaping from the top of the stomach
  • Stomach acid - Hydrochloric Acid ( HCl )
  • Digestive enzymes need acid conditions to work
  • Antacids neutralise excess stomach acid
    • they contain bases (stubstances that react with acid)
  • Some bases are soluble
    • base dissolved in water - alkali
  • Acid or alkali? - Indicator

acid + base ➝ salt + water

hydrochloic acid + calcium carbonate ➝ calcium chloride + water + carbon dioxide

      2HCl (aq)      +      CaCO(s)       ➝      CaCl2 (aq)      + H2O (l) +    CO2 (g)



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Neutralisation

  • Types of compounds to neutralise acid
    • metal oxides, metal hydroxides and metal carbonates


  • To manage spilt acid or alkali safely
    • dilute with water
    • neutralise it with metal compound

acid + metal oxide ➝ salt + water

acid + metal hydroxide ➝ salt + water

acid + metal carbonate  salt + water + carbon dioxide

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Importance of Chlorine

  • Yellow-green toxic gas with many uses
    • killing microorganisms - treating our water supply
    • manufacture bleach/other cleaning products
    • manufacture plastics e.g. polychlorothene (PVC)
  • Harmful to living things
  • Reacts with many coloured substances converting them to colourless
  • Potential problems
    • gas leak from a chemical factory
    • gas-carrying tanker involved in an accident
    • leaking toxic gas kills more people than an explosion
  • TEST FOR CHLORINE
    • damp blue litmus paper - red then bleached white
    • acidic = red       chlorine = bleached white
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Electrolysis

  • Some substances can be decomposed using electrical energy or heat energy
  • Decomposition of compounds can form new compounds
    • using heat THERMAL DECOMPOSITION
    • using electricity ELECTROLYSIS called electrolytes
  • Direct current passed through sea water
    • chlorine gas is produced
  • Direct current passed through dilute hydrochloric acid
    • hyrodgen gas chlorine gas are produced
  • Direct current passed through water
    • hydrogen gas and oxygen are given off
  • Hydrogen
    • used as rocket fuel (pure hydrogen)
    • lightest gas
  • Oxygen - mixed with fuel to make flames very hot
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