phosphorus

Phosphorus

source : Buzzle

Chemical properties of Phosphorus :

1) Ignition temperature:

It catches fire in air at ordinary temperature. Its flame is called cold flame.

4P + SO₂  —–> 2P₂O₅ or P4O₁₀

4P + 3O₂ ——-> 2P₂O₃ or P₄O₆

2) Reaction with Halogens:

Phosphorus trichloride and phosphorus pentachloride are formed.

2P + 3Cl₂  ——-> 2PCl₃

2P + 5Cl₂  —–>  2PCl₅

3) Reaction with Sulphur:

3S + 2P —-> P₂S₃

2P + 5S —–> P₂S₅

4) Reaction with NaOH:

In presence of inert atmosphere, phosphine is formed as main product.

P₄ + 3 NaOH + 3 H₂O  ———-> PH₃ (phosphine) + 3 NaH₂PO₂ (sodium hypo phosphite)

P₄ + 4 NaOH + 4 H₂O ——–> 2 H₂ + 4NaH₂PO₂

3 P₄ + 8 NaOH + 8 H₂O  ———-> 2 P₂H₄ (phosphorus dihydride) + 8 NaH₂PO₂

some H₂ and P₂H₄ is obtained as impurity.

Effect of heat:

In presence of inert atmosphere,

white P₄ ——–> Red P₄  (at 240^oC)

Red P₄ ———-> white P₄ (at 290^oC)

Reducing properties:

1. Reaction with copper sulphate solution:

a) On heating : Cuprous phosphide is obtained.

3 CuSO₄ + 3 P+ 6 H₂O ——–> Cu₃P (cuprous phosphide) + 3 H₂SO₄ + 2 H₃PO₃

b) At ordinary temperature: Precipitates of copper are formed.

10 CuSO₄ + 4P + 16 H₂O ——-> 10  Cu + 4 H₃PO₄ + 10 H₂SO₄

2) Reaction with HNO₃:

[2HNO₃ ——-> H₂O + 2NO₂ + O ] x 5

10HNO₃ ——–> 5H₂O + 5[O] + 10NO₂

2P + 5[O] + 3H₂O —–> 2H₃PO₄

10 HNO₃ + 2P ———> 2H₃PO₄ + 10NO₂ + 2H₂O

3)  Reaction with H₂SO₄:

[H₂SO₄ ——-> H₂O + SO₂ + [O] ] x 5

5H₂SO₄ ——-> 5H₂O + 5SO₂ + 5[O]

2P + 5[O] + 3H₂O ——-> 2H₃PO₄

5 H₂SO₄ + 2P ——-> 2H₂O + 5SO₂ + 2H₃PO₄

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