Acids, Bases and Salts C4

• Acids


  Solutions contain hydrogen ions
• Acidic solution


  • pH number less than 7
  • Yellow litmus paper turns red
  • Methyl orange turns red
• Acid reactions


  • React with metal to produce hydrogen gas
  • React with base to produce salt and water
• Sulphuric Acid, Hydrochloric Acid, Nitric Acid, Ethanoic Acid

  • H2SO4
  • HCl
  • HNO3
  • CH3COOH
• Neutralization of acids and bases

  1. Acid + Base → Salt + Water

  2. Carbonate + Acid → Salt + Water + Carbon Dioxide
• Bases


  • Oxides or hydroxides of metals
  • Alkaline solutions have pH greater than 7
• Alkaline solution


  • Universal indicator turns purple
  • Litmus paper turns blue
  • Methyl orange turns yellow
  • Phenolphthalein turns pink
• Reaction of acids and bases

  1. Acid + Base → Salt + Water

  2. Acid + Metal hydroxide → Salt + Water
• Oxides


  Compounds made from one or more atoms of oxygen combined with one other element
• Acidic oxides


  • Formed when a non-metal element combines with oxygen
  • React with bases to form a salt and water
  • Produce acidic solutions in water
• Basic oxides


  • Formed when a metal element combines with oxygen
  • React with acids to form a salt and water
  • Produce basic (alkaline) solutions in water
• Amphoteric oxides


  • React with both acids and bases to produce a salt and water
• Preparation of salts


  1. Reaction of acid and metal/insoluble base/insoluble carbonate

  2. Filtration

  3. Evaporation to crystallize
• Preparation of salts by titration

  1. Mix alkali and acid in a conical flask with indicator

  2. Add acid to alkali until indicator changes colour

  3. Calculate volume of acid used

  4. Repeat without indicator and evaporate to get salt
• Preparation of insoluble salts by precipitation

  1. Dissolve soluble salts and mix

  2. Filter to remove precipitate

  3. Wash precipitate with water and dry
• Hydrated substance


  Chemically bonded with water
• Anhydrous substance


  Containing no water