Phosphorus: Difference between revisions
imported>David E. Volk (fertilizers and allotropes) |
imported>David E. Volk (phosphine, diphosphine and phosphonium salts) |
||
| Line 5: | Line 5: | ||
== production of elemental phosphorus == | == production of elemental phosphorus == | ||
Calcium phosphate (phosphate rock), mostly mined in Florida and North Africa, can be heated to 1200-1500 Celcius with sand, which is mostly SiO<sub>2</sub>, and coke (impure carbon) to produce vaporized tetraphosphorus, P<sub>4</sub>, (mp. 44.2 C) which is subsequently condenced into a white power under water to prevent oxidation. Even under water, white phosphorus is slowly converted to the more stable red phosphorus [[allotrope]] (mp. 597C). Both the white and red allotropes of phosphoruus are insoluble in water. | Calcium phosphate (phosphate rock), mostly mined in Florida and North Africa, can be heated to 1200-1500 Celcius with sand, which is mostly SiO<sub>2</sub>, and coke (impure carbon) to produce vaporized tetraphosphorus, P<sub>4</sub>, (mp. 44.2 C) which is subsequently condenced into a white power under water to prevent oxidation. Even under water, [[white phosphorus]] is slowly converted to the more stable red phosphorus [[allotrope]] (mp. 597C). Both the white and red allotropes of phosphoruus are insoluble in water. | ||
== fertilizers == | == fertilizers == | ||
| Line 12: | Line 12: | ||
== allotropes of phosphorus == | == allotropes of phosphorus == | ||
Both phosphorus and arsenic have many allotropes, but only two forms predominate. White phosphorus and yellow arsenic both have four atoms arranged in a tetrahedral structure in which each atom is bound to the other three atoms by a single bond. This form of the elements are the least stable, most reactive, more volatile, less dense, and more toxic than the other allotropes. The toxicity of white phosphorus lead to its discontinued use in matches. In red phosphorus, one of the bonds in P4 described above have been broken, and one additional bond is formed with a neighboring tetrahedron. | Both phosphorus and arsenic have many allotropes, but only two forms predominate. White phosphorus and yellow arsenic both have four atoms arranged in a tetrahedral structure in which each atom is bound to the other three atoms by a single bond. This form of the elements are the least stable, most reactive, more volatile, less dense, and more toxic than the other allotropes. The toxicity of white phosphorus lead to its discontinued use in matches. In red phosphorus, one of the bonds in P4 described above have been broken, and one additional bond is formed with a neighboring tetrahedron. | ||
== phosphine, diphosphine and phosphonium salts == | |||
Phosphine (PH<sub>3</sub>) and arsine (AsH<sub>3</sub>) are structural analogs with ammomia (NH<sub>3</sub>) and form pyramidal structures with the phosphorus or arsenic atom in the center bound to three hydrogen atoms and one lone electron pair. Both are colorless, ill-smelling, toxic compounds. Phosphine is produced in a manner similar to the production of ammonia. Hydrolysis of calcium phosphide, Ca<sub>3</sub>P<sub>2</sub>, or calcium nitride, Ca<sub>3</sub>N<sub>2</sub> produce phosphine or ammonia, respectively. Unlike ammonia, phosphine in unstable and it reacts instantly with air giving off phosphoric acid clouds. Arsenic is even less stable. Although phosphine is less basic than ammonia, it can form a few some phosphonium salts (PH<sub>4</sub>I), analogs of ammonium salts, but these salts immediately decompose in water and do not yield PH<sub>4</sub><sup>+</sup> ions. Diphosphine (P<sub>2</sub>H<sub>4</sub> or H<sub>2</sub>P-PH<sub>2</sub>) is an analog of [[hydrazine]] (N2H4) that is a colorless liquid which spontaneously ignites in air and can disproportionate into phosphine and complex hydrides. | |||
== phosphorus halides == | |||
[[Category:CZ Live]] | [[Category:CZ Live]] | ||
[[Category:Chemistry Workgroup]] | [[Category:Chemistry Workgroup]] | ||
Revision as of 16:07, 6 December 2007
Phosphorus is a chemical element, with atomic number Z = 15, that is present in all living organisms in the form of organophosphates and as calcium phosphates such as hydroxyapetite (Ca10(PO4)6(OH)2) and fluoroapatite (Ca10(PO4)6F2) found in teeth and bones. Many cell signaling cascades in living organisms operate by a series of phosphorylation events in which a phosphate group (PO4)2- is either added to a protein by a kinase or removed from a protein by a phosphorylase. Unlike other elements in group VA, phosphorus is never found as a pure element in nature, but only in combination with other elements. Both red phosphorus and tetraphosphorus trisulfide are used in common matches because they are easily ignited by heat. However, the agricultural industry is the largest user of phosphorus in the form of fertilizers. Phosphorus and arsenic share many chemical properties.
production of elemental phosphorus
Calcium phosphate (phosphate rock), mostly mined in Florida and North Africa, can be heated to 1200-1500 Celcius with sand, which is mostly SiO2, and coke (impure carbon) to produce vaporized tetraphosphorus, P4, (mp. 44.2 C) which is subsequently condenced into a white power under water to prevent oxidation. Even under water, white phosphorus is slowly converted to the more stable red phosphorus allotrope (mp. 597C). Both the white and red allotropes of phosphoruus are insoluble in water.
fertilizers
Due to the essential nature of phosphorus to living organisms, the low solubility of natural phosphorus-containing compounds, and the slow natural cycle of phosphorous, the agricultural industry is heavily reliant on fertilizes which contain phosphate, mostly in the form of superphosphate of lime. Superphosphate of lime is a mixture of two phosphate salts, calcium dihyrogen phosphate (Ca(H2PO4)2) and calcium sulfate dihydrate CaSO4•2H2O produced by the reaction of sulfuric acid and water with calcium phosphate.
allotropes of phosphorus
Both phosphorus and arsenic have many allotropes, but only two forms predominate. White phosphorus and yellow arsenic both have four atoms arranged in a tetrahedral structure in which each atom is bound to the other three atoms by a single bond. This form of the elements are the least stable, most reactive, more volatile, less dense, and more toxic than the other allotropes. The toxicity of white phosphorus lead to its discontinued use in matches. In red phosphorus, one of the bonds in P4 described above have been broken, and one additional bond is formed with a neighboring tetrahedron.
phosphine, diphosphine and phosphonium salts
Phosphine (PH3) and arsine (AsH3) are structural analogs with ammomia (NH3) and form pyramidal structures with the phosphorus or arsenic atom in the center bound to three hydrogen atoms and one lone electron pair. Both are colorless, ill-smelling, toxic compounds. Phosphine is produced in a manner similar to the production of ammonia. Hydrolysis of calcium phosphide, Ca3P2, or calcium nitride, Ca3N2 produce phosphine or ammonia, respectively. Unlike ammonia, phosphine in unstable and it reacts instantly with air giving off phosphoric acid clouds. Arsenic is even less stable. Although phosphine is less basic than ammonia, it can form a few some phosphonium salts (PH4I), analogs of ammonium salts, but these salts immediately decompose in water and do not yield PH4+ ions. Diphosphine (P2H4 or H2P-PH2) is an analog of hydrazine (N2H4) that is a colorless liquid which spontaneously ignites in air and can disproportionate into phosphine and complex hydrides.