Properties of Red Phosphorous

Properties of Red Phosphorous:

In 1845, Schrotter first prepared a red variety of phosphorous by heating white phosphorous in a flask in an atmosphere of nitrogen or carbon dioxide gas.

Physical Properties of Red Phosphorous:

  • Red phosphorous is a violet-red amorphous powder.
  • It is a hard substance and its specific gravity is 2.2.
  • Its melting point is 600-615°C and its boiling point is very high. Its ignition temperature is 260°C.
  • It is insoluble in water as well as in carbon disulfide.
  • It is a poor conductor of electricity.
  • It is non-poisonous in nature.

Chemical Properties of Red Phosphorous:

Chemically, red phosphorous is less active than white phosphorous.

(1) Stability- Red phosphorous is a stable variety of phosphorous. It is stable towards heat.

(2) Combustion- Red phosphorous combines with oxygen at 260°C to give rise to the formation of phosphorous pentoxide (P2O5).

P4 + 5O2 ———> 2P2O5

(3) Action of non-metals- It combines with non-metals such as halogens, sulfur, etc. on heating to give the corresponding halides, sulfides etc.

P4 + 6Cl2 ———> 4PCl3 (Phosphorous trichloride)
P4 + 3S ———> P4S3 (Tetraphosphorous trisulfide)

(4) Action of metals- Red phosphorous combines with metals such as sodium, calcium, etc. on heating to give rise to the formation of the corresponding phosphides.

12Na + P4 ———> 4Na3P
6Ca + P4 ———> 4Ca3P2
6Cu + P4 ———> 2Cu3P2

(5) Action of alkalis- It has no action on hot concentrated alkalis like NaOH.

(6) Reducing Properties- Like white phosphorous, it reduces concentrated H2SO4 and HNO3.

P4 + 10H2SO4 ———> 10SO2 + 4H3PO4 + 4H2O
P4 + 20HNO3 ———> 20NO2 + 4H3PO4 + 4H2O

(7) Phosphorescence- Red phosphorous does not show the phenomenon of phosphorescence.

Uses of Red phosphorous:

It is used-

  • In the manufacture of safety matches.
  • In the production of phosphorous compounds.
  • In the manufacture of alloys like phosphor-bronze.
  • In the preparation of HBr, HI and organo halogen compounds.

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