Phosphine gas (PH3)

In the laboratory phosphine is prepared by heating white phosphorus with concentrated caustic alkali solution in an inert atmosphere of oil gas or CO2.
P4 + 3NaOH + 3H2O ------------> 3NaH2PO2 (Sodium hypophosphite) + PH3 (phosphine)
Metal phosphides on hydrolysis form phosphine
Ca3P2 + 6H2O ------------> 3Ca(OH)2 + 2PH3
A pure sample of phosphine can also be prepared by heating phosphorous acid
4H3PO3 ---------------> 3H3PO4 + PH3
Phosphine has pyramidal structure and is a weaker base than NH3

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