Spelling and etymology

Sulfur comes via Old French from Latin sulphur, which in turn is apparently formed on a root meaning "to burn". The element was traditionally spelledsulphur in the United Kingdom (since the 14th century), most of the rest of the Commonwealth (including Australia, India, Malaysia, South Africa),Hong Kong, the Caribbean and Ireland. Sulfur is used in the United States, while both spellings are used in Canada and the Philippines.

However, the IUPAC adopted the spelling sulfur in 1990, as did the Royal Society of Chemistry Nomenclature Committee in 1992. The Qualifications and Curriculum Authority for England and Wales recommended its use in 2000, and it now appears in GCSE exams. The Oxford Dictionaries note that "In chemistry... the -f- spelling is now the standard form in all related words in the field in both British and US contexts."

In Latin, the word is variously written sulpur, sulphur, and sulfur (the Oxford Latin Dictionary lists the spellings in this order). It is an original Latin name and not a Classical Greek loan, so the phvariant does not denote the Greek letter φ (phi). Sulfur in Greek is thion (θείον), whence comes the prefix thio-. The simplification of the Latin word's p or ph to an f appears to have taken place towards the end of the classical period.

Applications

Sulfuric acid

Elemental sulfur is mainly used as a precursor to other chemicals. Approximately 85% (1989) is converted to sulfuric acid (H₂SO₄):

2 S + 3 O₂ + 2 H₂O → 2 H₂SO₄

With sulfuric acid being of central importance to the world's economies, its production and consumption is an indicator of a nation's industrial development. For example with 32.5 million tonnes in 2010, the United States produces more sulfuric acid every year than any other inorganic industrial chemical. The principal use for the acid is the extraction of phosphate ores for the production of fertilizer manufacturing. Other applications of sulfuric acid include oil refining, wastewater processing, and mineral extraction.

Other large-scale sulfur chemicals

Sulfur reacts directly with methane to give carbon disulfide, which is used to manufacture cellophane and rayon. One of the direct uses of sulfur is in vulcanization of rubber, where polysulfidescrosslink organic polymers. Sulfites are heavily used to bleach paper and as preservatives in dried fruit. Many surfactants and detergents, e.g. sodium lauryl sulfate, are produced are sulfate derivatives. Calcium sulfate, gypsum, (CaSO₄^·2H₂O) is mined on the scale of 100 million tons each year for use in Portland cement and fertilizers.

When silver-based photography was widespread, sodium and ammonium thiosulfate were widely used as "fixing agents." Sulfur is a component of gunpowder.

Fertilizer

Sulfur is increasingly used as a component of fertilizers. The most important form of sulfur for fertilizer is the mineral calcium sulfate. Elemental sulfur is hydrophobic (that is, it is not soluble in water) and, therefore, cannot be directly utilized by plants. Over time, soil bacteria can convert it to soluble derivatives, which can then be utilized by plants. Sulfur improves the use efficiency of other essential plant nutrients, particularly nitrogen and phosphorus. Biologically produced sulfur particles are naturally hydrophilic due to a biopolymer coating. This sulfur is, therefore, easier to disperse over the land (via spraying as a diluted slurry), and results in a faster release.

Plant requirements for sulfur are equal to or exceed those for phosphorus. It is one of the major nutrients essential for plant growth, root nodule formation of legumes and plants protection mechanisms. Sulfur deficiency has become widespread in many countries in Europe. Because atmospheric inputs of sulfur continue to decrease, the deficit in the sulfur input/output is likely to increase, unless sulfur fertilizers are used.

Fine chemicals

Picture 11. A molecular model of the pesticidemalathion.

Organosulfur compounds are used in pharmaceuticals, dyestuffs, and agrochemicals. Many drugs contain sulfur, early examples being antibacterialsulfonamides, known as sulfa drugs. Sulfur is a part of many bacterial defense molecules. Most β-lactam antibiotics, including the penicillins,cephalosporins and monolactams contain sulfur.

Magnesium sulfate, known as Epsom salts when in hydrated crystal form, can be used as a laxative, a bath additive, an exfoliant, magnesiumsupplement for plants, or (when in dehydrated form) as a desiccant.

Date: 2016-04-22; view: 1644