Phosphorus

Phosphorus, is called ‘spreader of light’ in Latin language. It is very reactive nonmetal. It is essential constituent of living organisms, found in bones and teeth. Many proteins, in seeds, eggs, nerve tissues and brain cells contain phosphorus. It makes up 1% of human body.

White-yellow waxy solid. Ignites in moist air, stored under water. P 4 tetrahedral structure. Poisonous, unstable. Garlic smell. illuminates at night. Does not conduct electricity. Insoluble in water. Allotropes of Phosphorus White Phosphorus Red Phosphorus White- Red powder. Ignites in air above C. Not poisonous. No smell. No illumination. Sublimes at C. Used on match boxes.

Exist in nature as PO 4 -3 minerals. The most abundant is Ca 3 (PO 4 ) 2 and apatite CaF 2. 3Ca 3 (PO 4 ) 2. Very important for living organisms, exist in skeleton and teeth as Ca 3 (PO 4 ) 2 intensively.

Occurrence of Phosphorus White phosphorus is sometimes called yellow phosphorus because it turns lemon-yellow on exposure to light. It changes slowly and spontaneously to red phosphorus. P (white) → P (red) Black phosphorus is the most stable allotrope of phosphorus. Obtained by heating white phosphorus under high pressure. It is semiconductor. 300 o C I2I2

White phosphorus is prepared by heating mixture of sand, coke and calcium phosphate in electric furnace to about C. 2Ca 3 (PO 4 ) 2 (s) + 6SiO 2 (s) → 6CaSiO 3 (s) + P 4 O 10 (g) P 4 O 10 (g) + 10C(s) → P 4 (g) + 10CO(g) Heat The phosphorus vapor is obtained from the above reactions condensed to a liquid under water, and than further cooled and pressed into sticks.

Chemical Properties of Phosphorus Reacts with some metals; 3Ba + 2P → Ba 3 P 2 Reacts with halogens; 2P + 5I 2 → 2PI 5 Forms P 2 O 3 or P 2 O 5 with oxygen; P 4 + 3O 2 → 2P 2 O 3 Reacts with strong acids; P 4 + 5HNO 3 → H 3 PO 4 + 5NO 2 + H 2 O Reacts with strong bases; 2P 4 + 3Ba(OH) 2 + 6H 2 O → 2PH 3 + 3Ba(H 2 PO 2 ) 2

Oxides, P 4 O 6 White crystalline, wax-like solid. Its vapor smells like garlic and poisonous. Prepared by the reaction; P 4 (s) + 3O 2 (g) → P 4 O 6 (s) Dissolves slowly in cold water. P 4 O 6 + 6H 2 O → 4H 3 PO 3 6P 4 O H 2 O → 15H 3 PO 3 + PH 3 + 8P(red) Reacts with nonmetals. P 4 O 6 + 6Cl 2 → 4POCl 3 + O 2 Compounds of Phosphorus

Oxides, P 4 O 10 White crystalline, White solid formed by reaction of oxygen with P 4.React with water vigorously. P 4 + 5O 2 → P 4 O 10 P 4 O 10 (s) + 6H 2 O(l) → 4H 3 PO 4 (aq) Hot Phosphoric Acid, H 3 PO 4 Colorless solid, Sold as solution of water, Used in fertilizers, soft drinks, detergent, Obtained by the reaction, P 4 O 10 (s) + 6H 2 O(l) → 4H 3 PO 4 (aq)

Uses of Phosphorus In fertilizers, pesticides, detergents, water softeners, baking powder, fireworks and match boxes…etc