Acids and Bases

A mindmap for unit 10 of the CIE IGCSE Chemistry specification, 'Acids and Bases'. 

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  • Created by: steph
  • Created on: 22-03-13 20:02
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  • Acids and Bases
    • Hydrogen and hydroxide ions
      • All acids form H+ ions when dissolved in water
    • The pH scale
      • Acids have a pH below 7
        • Lower pH = more hydrogen ions
      • Alkalis have a  pH above 7
        • Higher pH = more hydroxide ions
      • pH can be measured with universal indicator paper
        • Mixture of indicators showing a range of colours depending on pH
    • Properties of acids
      • Turns blue litmus red
      • React with metals to form a salt and hydrogen
        • Salt = compound formed when metal or ammonium group replaces hydrogen in acid
      • React with metal  oxides and hydroxides to form a salt and water
      • React with carbonates (and hydrogencarbonates) to form a salt, water and carbon dioxide
    • Bases
      • Substances that can react with acids
      • Oxides, hydroxides or carbonates of metals
      • Alkalis are bases that are soluble in water
      • Metal carbonates react with acids to form a salt, water and carbon dioxide
      • Metal oxides and hydroxides react with acids to form a salt and water
      • When base reacts with acid and salt forms: neutralisation
      • Alkalis react with ammonium salts to form a metal salt, ammonia and water
    • Soil acidity
      • Excess acidity can be removed  with bases
      • Products used to remove acidity e.g. (Calcium carbonate) have neutral products
    • Acids, bases and protons
      • Hydrogen ion = just a proton
      • Acid = proton donor
        • Gives a proton to a base
      • Base = proton acceptor
        • Removes protons from an acid
    • Strong and weak acids
      • Strong: completely ionise when dissolved in water
        • Good electrical conductivity, faster reaction time
      • Weak: partly ionise when dissolved in water
        • Strong acid has lower pH than weak acid of same conc.
    • Strong and weak bases
      • Hydroxides of alkali metals are strong bases
        • Completely ionised in water
      • Weak bases have lower electrical conductivity, lower pH, slower reaction rate
    • Oxides
      • Basic oxides
        • Most metal oxides
        • React with acids to form salt and water
        • They do not react with alkalis
      • Acidic oxides
        • Most non-metal oxides
        • React with alkalis to form salt and water, and water to form acidic solutions
        • Some react with bases when heated
      • Neutral oxides
        • No reaction with acids or bases
        • 'Lower' non-metal oxides e.g. CO (CO2 is acidic)
      • Amphoteric oxides
        • Acidic and basic properties
        • React with acids to form salts, react with alkalis to form complex salts


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