Group IV Oxides

Group IV Oxides

Structure

  • a) CO2 - molecular
  • b) SiO2 - macromolecular
  • c) GeO2, SnO2, PbO2 - intermediate between ionic and macomolecular

Acidity

  • a) CO2 and SiO2 are acid and react with alkalis to form salts.
CO2(g) + 2NaOH(aq) → Na2CO3(aq) + H2O(l)
  • b) GeO, SnO2 and PbO2 are amphoteric and will react with both acids and alkalis.
SnO2(s) + conc.HCl(l) → SnCl4(l) + 2H2O(l)
SnO2(s) + 2OH-(aq) → SnO32-(aq) + H2O(l)

Thermal stability

They are very stable to high temperature except PbO2 which readily loses O2.

2PbO2(s) → 2PbO(s) + O2(g)

Structure

  • a) CO and SiO are molecular. CO has a lone pair of electrons hence, can act as a ligand forming complexes with transition metals. For example: Ni(CO)42+
  • b) GeO, SnO, PbO are mainly ionic.

Acidity

  • a) CO and SiO are neutral and react neither with acids or alkalis.
  • b) GeO, SnO, PbO are amphoteric.
SnO(s) + 2HCl(aq) → SnCl2(aq) + H2O(l)
SnO(s) + 2OH-(aq) → [Sn(H204)4]2-(aq)

Thermal stability

The only stable one is PbO. The others are readily oxidised on standing in air to the dioxide.

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