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