Acidic Oxides

Identify oxides of non-metals which act as acids and describe the conditions under which they act as acids

  • Oxides can be classified as acidic, basic, amphoteric or neutral.
    • Acidic oxides: Oxides that display one or both of the following properties:
      • React with bases to form salts.
      • React with water to produce acids.
    • Basic oxides: Oxides that display the following properties:
      • React with acids to produce salts.
      • If soluble, react with water to produce alkaline solutions.
      • Do not react with alkaline solutions.
    • Amphoteric oxides: Oxides that react with both acids and bases.
    • Neutral oxides: Oxides that do not react with either acids or bases.
  • Acidic oxides are generally formed by non-metals
  • Basic oxides are generally formed by metals.
  • Examples of acidic oxides are:
    • Carbon dioxide (CO2).
    • Diphosphorus pentoxide (P2O5).
    • Nitrogen dioxide (NO2).
  • Acidic oxides act as acids when they dissolve in wate.
  • For example, carbon dioxide reacts with water to produce carbonic acid:

  • This is the reason why indicator paper must be moist in order to detect whether a non-metal oxide gas is acidic.

Easychem - Acidic Oxides