Chemical Properties of Bases/Alkalis
- Alkalis react with acids to form a salt and water — this is a neutralisation reaction:
- 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 + HNO3 → KNO3 + H2O
Alkali heat with Ammonium Salts
Ammonium Salt + Alkali → Salt + Ammonia + Water
Example:
Ammonium Chloride + Sodium Hydroxide → Sodium chloride + Water + Ammonia
NH4Cl + NaOH → NaCl + H2O + NH3
More examples:
2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3
(NH4)2SO4 + 2NaOH→ Na2SO4 + 2H2O+ 2NH3
Ammonia as an Alkali
- By nature, ammonia is a covalent compound.
- Ammonia exists as gas at room temperature.
- Ammonia gas is soluble in water.
- Physical properties of ammonia:
- Pungent smell
- Colourless
- Turn litmus from red to blue