Chapter:

Oxides of phosphorus: Preparation, properties, Structure

1. Phosphorus trioxide : It is obtained by the combustion of phosphorus in a limited supply of air. , 2. Phosphorus trioxide : Phosphorus pentoxide can be prepared by burning phosphorus with sufficient supply of air.

Phosphorus -

Atomic Number : 15 Electronic Configuration : [Ne] 3s2 3p3 Group Number : 15 Periodic Number : 3

Oxides of phosphorus

I Phosphorus trioxide P2O3 or P4O6

It is obtained by the combustion of phosphorus in a limited supply of air.

4P + 3O2 � 2P2O3

Physical properties

1. It is a white waxy substance

2. It has a garlic odour.

Chemical properties

1. It reacts with cold water, gives phosphorus acid.

P2O3 +3H2O � 2H3PO3

2. It reacts with hot water vigorously to form inflammable phosphine.

2P2O3 + 6H2O � PH3 � + 3H3 PO4

II Phosphorus pentoxide P2O5 or P4O10

Phosphorus pentoxide can be prepared by burning phosphorus with sufficient

supply of air.

P4 + 5O2 �P4 O10

Physical properties

It is a white solid and an acidic oxide.

Chemical properties

1. It reacts with moisture to form metaphosphoric acid.

P4O10 + 2H2O � 4HPO3

When the solution is boiled, the metaphosphoric acid is changed to

orthophosphoric acid.

HPO3 + H2O � H3PO4

P4O10 + 6H2O � 4H3 PO4

2. Phosphorus pentoxide extracts water from many inorganic compound

including sulphuric acid, nitric acid and several organic compounds. It is therefore, used as a powerful dehydrating agent.

Use: It is used as a dehydrating agent.

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: Oxides of phosphorus: Preparation, properties, Structure |