Phosphine, Phosphorus Trichloride, Phosphorus pentachloride

Phosphorus forms two types of halides, PX₃ (X = F, Cl, Br, I) and PX₅ (X = F, Cl, Br).

Phosphorus trichloride, PCl₃
Phosphorus pentachloride, PCl₅

	Phosphine, PH₃	Phosphorus Trichloride, PCl₃	Phosphorus pentachloride, PCl₅
Explain	Phosphine is a highly poisonous, colourless gas and has a smell of rotten fish.	This is a type of halides. It is a colourless oily liquid.	It is molecular in gas and liquid phase, but in solid state exists as [PCl₄]⁺ PCl₆]^– containing tetra and hexa-coordinated phosphorous species.
Preparation	Phosphine is prepared by the reaction of calcium phosphide with water or dilute HCl.	It is obtained by passing dry chlorine over heated white phosphorus or by the action of thionyl chloride with white phosphorus.	Phosphorus pentachloride is prepared by the reaction of white phosphorus with excess of dry chlorine or can be prepared by the action of SO₂Cl₂ on phosphorus.
Properties	It is insoluble in water and is a weaker base than ammonia. Like ammonia, it gives phosphonium compounds with acids. For example: PH₃ is non-inflammable when pure but becomes inflammable owing to the presence of P₂H₄ or P₄ vapours. In water, PH₃ decomposes in the presence of light to give red phosphorus and H₂.	It has a pyramidal shape, in which phosphorus is sp³ hybridised. It gets hydrolysed in the presence of moisture.	In gaseous and liquid phases, its has a trigonal bipyramidal structure.PCl₅ is a yellowish white powder and in moist air, it hydrolyses to POCl₃ and finally gets converted to phosphoric acid.When heated, it sublimes but decomposes on stronger heating.

Phosphine, PH₃

Phosphorus Trichloride, PCl₃

Phosphorus pentachloride, PCl₅

Explain

Phosphine is a highly poisonous, colourless gas and has a smell of rotten fish.

This is a type of halides.
It is a colourless oily liquid.

It is molecular in gas and liquid phase, but in solid state exists as [PCl₄]⁺ PCl₆]^– containing tetra and hexa-coordinated phosphorous species.
Phosphorus pentachloride

Preparation

Phosphine is prepared by the reaction of calcium phosphide with water or dilute HCl.

It is obtained by passing dry chlorine over heated white phosphorus or by the action of thionyl chloride with white phosphorus.
Phosphorus Trichloride

Phosphorus pentachloride is prepared by the reaction of white phosphorus with excess of dry chlorine or can be prepared by the action of SO₂Cl₂ on phosphorus.

Properties

It is insoluble in water and is a weaker base than ammonia. Like ammonia, it gives phosphonium compounds with acids. For example:

PH₃ is non-inflammable when pure but becomes inflammable owing to the presence of P₂H₄ or P₄ vapours.
In water, PH₃ decomposes in the presence of light to give red phosphorus and H₂.

It has a pyramidal shape, in which phosphorus is sp³ hybridised.
It gets hydrolysed in the presence of moisture.

In gaseous and liquid phases, its has a trigonal bipyramidal structure. Phosphorus pentachloride

PCl₅ is a yellowish white powder and in moist air, it hydrolyses to POCl₃ and finally gets converted to phosphoric acid. Phosphorus pentachloride

When heated, it sublimes but decomposes on stronger heating.

Comparison between Phosphine and Ammonia

Property	Phosphine	Ammonia
Colour	Colourless	Colourless
Decomposition by electric spark	Decomposes into elements	Decomposes into elements
Action with chlorine	Reacts violently to form PCl₅	Reacts with chlorine to form nitrogen trichloride
Action with halogen acids	Forms phosphonium salts	Forms ammonium salts
Combustibility	Burns in air to form phosphoric acid	Burns in air to form nitrogen and water.
Smell	Unpleasant smell of rotten fish.	Characteristic ammoniacal smell.
Density	Heavier than air	Lighter than air
Solubility	Sparingly soluble in water	Highly soluble in water
Nature	Highly poisonous	Non- poisonous
Action towards	Neutral	Basic
Stability	Less stable	More stable
Stability of salts	Less	More

Comparison between Phosphine and Ammonia

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