Question

The gas phosphine (PH3) is used as a fumigant to protect stored grain and other durable produce from pests. Phosphine is generated where it is to be used by adding water to aluminum phosphide or magnesium phosphide. Give formulas for these two phosphides.

Answer 1

1) Molecular formula for aluminium phospide is AlP. Aluminium has oxidation number +3 (metal from 13. group of periodic table) and phosphorus in phospides has oxidation number -3.

Aluminium phosphide is a highly toxic, solid inorganic compound.

2) Molecular formula for aluminium phospide is Mg₃P₂. Magnesium has oxidation number +2 (metal from 2. group of periodic table) and phosphorus in phospides has oxidation number -3.