Question

A white waxy solid A on reduction gives B,having rotten fish smell. B on halogenation gives C which on hydrolysis gives an acidic compound D . if A on heating under inert atmosphere gives E,which is allotrope of A. Find A,B,C,D. Also give the chemical reaction involved.

Answer 1

A=Translucent waxy solid is actually white phosphorus (P4)
E=P4 on heating gives red phosphorus in inert atmosphere

P4 on excess of chlorine gives PCl5 which on hydrolysis gives POCl3 and H3PO4

P4 + 10Cl2 ⇒ 4PCl5
PCl5 + H2O ⇒ POCl3 + 2HCl
POCl3 + 3H2O ⇒ H3PO4 + 3HCl
ie,
C=PCl5
D=POCl3 and H3PO4 (acidic)

P4 + KOH + H2O ⇒ PH3 + KH2PO2
ie,
B=PH3