Chemical Properties of Bases/Alkalis


  1. Alkalis react with acids to form a salt and water — this is a neutralisation reaction:
  2. Alkalis, when warmed with ammonium salts, give off ammonia gas:

Reaction between Alkalis and Acids

Acid + Alkali  Salt + Water

Example:
Potassium hydroxide + Nitric Acid  Potassium Nitrate + Water
KOH + HN O 3   KN O 3  +  H 2 O

Alkali heat with Ammonium Salts

Ammonium Salt + Alkali  Salt + Ammonia + Water

Example:
Ammonium Chloride + Sodium Hydroxide  Sodium chloride + Water + Ammonia

N H 4 Cl + NaOH  NaCl +  H 2 O + N H 3
More examples:
2NH 4 Cl +    Ca ( OH ) 2  CaC l 2 +2 H 2 O+ 2N H 3
( NH 4 ) 2 SO 4 +   2NaOH+N a 2 S O 4 +2 H 2 O+ 2N H 3

Ammonia as an Alkali

  1. By nature, ammonia is a covalent compound.
  2. Ammonia exists as gas at room temperature.
  3. Ammonia gas is soluble in water.
  4. Physical properties of ammonia:
    1. Pungent smell
    2. Colourless
    3. Turn litmus from red to blue


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