this is because of strain in sp3 hybridised p4 molecule.the angle bw p &p is only 60°
as compared to the normal tetrahedral angle of 128°.thus it extrmely unstable and hence reactive.this is the teason it has a low ignition temp and catches fire spontaneously..
Why is the ignition temperature of white phosphorus v low?
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5 Answers
rocky
·2010-01-24 03:56:44
i just only know that
It ignites spontaneously in air at about 50 °C, and at much lower temperatures if finely divided. This combustion gives phosphorus (V) oxide:
P4 + 5O2 -> P4O10
Because of this property, white phosphorus is used as a weapon.
keshavgupta
·2010-01-28 02:08:11
Shirsa Aich
·2010-01-31 05:26:40
IN WHITE PHOSPHORUS MOLECULE(TETRAHEDRAL STRUCTURE) THE 4 P ATOMS ARE LOCATED AT THE 4 CORNERS OF A TETRAHEDRON.THE ANGLE BETWEEN 2 P ATOMS IS 60°BUT THE ANGLE BETWEEN 2 p ORBITALS SHOULD BE 90°,SO DUE TO INTERNAL STRAIN IT HAS A TENDANCY TO BREAK INTO ATOMS.SO ON APPLYING SLIGHT AMOUNT OF HEAT ENERGY IT STARTS BURNING.