Salts

• Salt


  A substance formed when an acid is neutralized by a base
• Salt


  • Contains a metal (cation from the base) and a non-metal or radical (anion from the acid)

  
• Acid salt


  Still contains some replaceable H+ from the acid, has a pH below 7
• Normal salt


  Contains no replaceable H+ ions, has a pH of 7 or neutral
• Hydrated salt


  Contains water within its crystal structure
• Thermal decomposition of salts

  1. Carbonates → Oxide + Carbon dioxide

  2. Hydrogencarbonates → Carbonate + Water + Carbon dioxide

  3. Nitrate → Oxide + Nitrogen dioxide + Oxygen

  4. Hydroxide → Oxide + Water
• Thermal dissociation


  When a compound decomposes on heating but the products rejoin on cooling
• Double decomposition


  Two salt solutions are added together and the ions exchange, forming an insoluble precipitate
• Ionic equation


  General equation representing ions taking part in a reaction, leaving out spectator ions
• Solubility rules


  • All nitrates are soluble, except oxynitrates of antimony and bismuth
  • All chlorides, bromides and iodides are soluble except those of silver, lead and mercurous mercury
  • All sulphates are soluble except those of barium, strontium and lead
  • All salts of sodium, potassium and ammonium are soluble
  • All carbonates are insoluble except those of sodium, potassium and ammonium
  • All phosphates are insoluble except those of sodium, potassium and ammonium
  • All sulphides are insoluble except those of ammonium, sodium, calcium, potassium, magnesium, barium and strontium
  • All hydroxides and oxides are insoluble except those of sodium, potassium, ammonium and barium