Class 12 Chemistry P Block Elements Phosphine


Its molecular formula is PH3

Its structure is:




It is prepared by dropping water on calcium phosphide.


Lab preparation: By disproportionate reaction


This phosphine produced can be purified by reacting it with HI to get PH4I and then this  PH4I react with KOH to form pure PH3 ,KI and water.


Physical properties:

  • It is colorless gas with smell of rotten fish.
  • It is poisonous.
  • It is slightly soluble in water.
  • The solution of phosphine is unstable and decomposes in presence of light.

    Chemical properties

  1. It is weakly basic due to lone pair of electrons.
  2. It undergoes precipitation reaction that is:


Uses of phosphine:

(a) Combustion of PH3is used in Holmes’s signals for ships.

(b)It is also used as smoke screens in warfare.

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