Comparison between White and Red Phosphorous

Comparison between White and Red Phosphorous:

A comparison of characteristics of white and red phosphorous is given in the following table-

Physical Characteristics:
PropertyWhite PhosphorousRed Phosphorous
Physical StateSoft, crystalline solid which can be cut with a knife.Amorphous powder.
ColourWhite when pure, on exposure to air, it acquires a yellowish tinge.Reddish Violet.
SmellGarlic like smell.No smell.
HardnessSoft waxy solid.Brittle solid.
SolubilitySoluble in carbon disulfide but insoluble in water.Insoluble in water and carbon disulfide.
Ignition Temperature35°C260°C
Melting Point44°C600-615°C
Boiling Point290°CVery high.
Physiological ActionPoisonous.Non-poisonous.
Electrical ConductivityVery poor.Poor.
HygroscopyNon-hygroscopic.Highly hygroscopic.
Crystalline StructureRhombohedral and P4 molecules.Cubic and macromolecular structure of P4 units.
Exposure to airUndergoes oxidation.No oxidation.
Chemical Characteristics:
PropertyWhite PhosphorousRed Phosphorous
StabilityUnstable and gradually changes into red phosphorous.Stable.
Chemical ActivityMore reactive in nature.Less reactive in nature.
CombustionBurns in the air to give P2O5.Burns at 260°C to give P2O5.
Action of alkalis like NaOHForms phosphine gas and sodium hypophosphite.No action.
Action of halogensForms halides readily.Forms halides on heating only.
Action of SulfurForms phosphorous trisulfide readily.Forms phosphorous trisulfide on heating only.
Reducing propertiesWith conc. HNO3 Reduces nitric acid to give o-Phosphoric acid.
With conc. H2SO4 o-Phosphoric acid is formed.
With conc. HNO3 Reduces HNO3 to give o-Phosphoric acid.
With conc. H2SO4 o-Phosphoric acid is formed.
PhosphorescenceShow the phenomenon of phosphorescence on exposure to air.Do not show phosphorescence.
Inter conversionChanges to red phosphorous on heating at 250°C in an inert atmosphere.Changes to white phosphorous when its vapours at 290°C are condensed in water.

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