Sulfur

MELTING POINT: 115.2°C
BOILING POINT: 444.6°C
DENSITY: 2.06 g/cm ³
MOST COMMON IONS: S ²⁻ , S ₂ O ₃ ²⁻ , SO ₃ ²⁻ , S ₂ O ₆ ²⁻ , SO ₄ ²⁺

Sulfur has been known since prehistoric times. Because it is flammable, alchemists regarded sulfur as essential to combustion . The chemical properties of sulfur and its compounds, including the reaction of sulfur with mercury (Hg) to form a red solid, mercuric sulfide (HgS), and the use of sulfuric acid (H ₂ SO ₄ ) as a solvent of metals , were discovered at about C.E. 250–300. Gunpowder, a mixture of sulfur, charcoal, and potassium nitrate (KNO ₃ ), was first used for military purposes in China in C.E. 904.

Sulfur is a tasteless, odorless, nonmetallic element. Sulfur along with selenium (Se) and tellurium (Te) are called chalcogens. The valences of sulfur are 2, 4, and 6, which can be represented by compounds such as hydrogen sulfide (H ₂ S), sulfur dioxide (SO ₂ ), and barium sulfate (BaSO ₄ ), respectively. Pure sulfur is insoluble in water. The most stable variety of sulfur, rhombic sulfur, is a yellow crystalline solid.

A vat of sulfur in Port Sulphur, Louisiana. Sulfur is an important crop nutrient and is the thirteenth most abundant element in Earth's crust.

In Earth's crustal composition, sulfur ranks thirteenth in abundance, with an estimated concentration of 0.05 percent. Sulfur exists in elemental form, as metallic sulfides, as sulfates, and, when combined with carbon and nitrogen, in organic forms. Most of the world's sulfur resource is located in North America. It is distributed, in descending order according to share of that resource, as follows: the United States and Canada have 26 percent and 22 percent, respectively, followed by Russia (11%), Saudi Arabia (5%), Japan (5%), Poland (4%), Germany (4%), and France (2%); the remaining 21 percent is distributed in other countries.

Sulfur is commercially important in the manufacture of chemicals such as sulfuric acid. The chemicals, in turn, are used in the manufacture of sulfa drugs, vulcanized rubber , acid batteries, dyes, and so on. In agriculture, sulfur is the fourth most important crop nutritive element, after nitrogen, phosphorus, and potassium. Its use in fertilizers is increasing rapidly. Sulfur is also used to manufacture poultry feed additives, pesticides, and parasiticides.

SEE ALSO Chalcogens .

Guang Wen

Bibliography

Hampel, Clifford A., and Hawley, Gessner G. (1976). Glossary of Chemical Terms. New York: Van Nostrand Reinhold.

Tisdale, Samuel L.; Nelson, Werner L.; and Beaton, James D. (1985). Soil Fertility and Fertilizers, 4th edition. New York: Macmillan.