source : slide player
Minerals of phosphorus:
Phosphorite or phosphate rock – [ Ca3 (PO4)2 ]
Fluor apatite – [ 3Ca3(PO4)2 . CaF2]
Chlor apatite – [3Ca3(PO4)2 . CaCl2]
Extraction of white phosphorus:
There are two method for extraction—
Retort process: (How can you prepare white P from phosphate rock?)
Bone ash is heated with H2SO4 then orthophosphoric acid is obtained which on strong heating gives metaphosphoric acid.
Ca3(PO4)2 + 3H2SO4 ——-> 2H3PO4 + 3CaSO4
H3PO4 ——> HPO3 (meta phosphoric acid) + H2O
Meta phosphoric acid is mixed with coke and then distilled.
4HPO3 + 10 C ——> 2H2O + P4 (phosphorus (white))+ 10 CO
Vapors of phosphorus are condensed in water. White P is insoluble in H2O therefore it settles down in the form of solid.
Mixture of calcium phosphate, silica and coke is heated in an electric furnace. Electric furnace contains carbon electrode. On passing current temperature rises upto 1500o C and following reactions takes places:-
Ca3(PO4)2 (bone ash) + 3SiO2 ——–> 3 CaSiO3 (slag) + P2O5
2 P2O5 + 10C —–> P4 (white phosphorus) + 10CO
Calcium silicate is removed as slag. The vapors of phosphorus are condensed in water. White P is insoluble in H2O. Therefore it settles down in the form of solid.
Allotropes of phosphorus:
It exists in the following allotropic forms :
1) white or yellow P
2) Red P
3) Violet P
4) Black P
5) Scarlet P
source : 2012 Book Archive
Physical properties :
- White P(is called phosphorus) is colorless, soft and wax like solid. It can be cut by a knife. It turns yellow on long standing.
- It has garlic like odor.
- It is insoluble in H2O but soluble in benzene, chloroform, ether, alcohol , CS2.
- Ignition temperature of white P is 300C. Therefore it catches fire immediately in air.
- On burning in air it forms poisonous fumes of P2O5. Therefore it is kept in water.
- It is poisonous in nature. Vapors of P are injurious to health . Persons working in the factory of phosphorus develop a disease ‘phossy jaw’.
- Melting point of white P is 44o C and boiling point is 287 oC.