Sarah Vanduyn

11/4/05

5^th/science

Element report

SULFUR

NAME: SULFUR

HISTORY OF NAME: CAME FROM THE SANSKRIT WORD SURVERE, SULURIUM, MEANING SULFUR.

WHEN IT WAS DISCOVED AND BY WHOM: IT HAS BEEN AROUND SINCE ANCHIENT TIMES.

USES: ITS USED FOR MATCHES GUN POWDER ANND MEDACINE.

COMMON COMPOUNDS: CARBON DISULFIDE AND GUNPOWDER.

WHERE IS IT FOUND: ITS FOUND IN UNDERGROUND SALT DOMES AND IN NATURAL GAS AND CRUDE OIL.

ATOMIC WEIGHT: 32.06

ATOMIC MASS: 32.066 AMU

ATOMIC NUMBER: 16

NUMBER OF PROTON, NEUTRONS, AND ELECTRONS: 16

Other information:

Sulfur is widely dispersed in nature. It is found in many minerals and ores, e.g., iron pyrites, galena, cinnabar, zinc blende, gypsum, barite, and epsom salts and in mineral springs and other waters. It is found uncombined in some volcanic regions and in large underground deposits in Sicily and in Texas and Louisiana. Sulfur sometimes is made with coal, petroleum, and natural gas. Sulfur is found in meteorites, and deposits of it may be present near the lunar crater Aristarchus. The distinctive colors of Jupiter's moon Io are believed to result from forms of molten, solid, and gaseous sulfur. Sulfur is a component of all living cells. The amino acids cysteine, methionine, homocysteine, and taurine contain sulfur as do some common enzymes; it is a component of most proteins. Some forms of bacteria use hydrogen sulfide (H₂S) in place of water in a rudimentary photosynthesislike process. Sulfur is absorbed by plants from soil as sulfate ions.

Sulfur is produced chiefly by the Frasch process, although it is also produced by the Sicilian method and by other methods. In the Sicilian method the sulfur-bearing ores are piled in a mound and ignited. The heat produced by the burning melts some of the sulfur, which is collected and cast. This sulfur is impure and is usually purified by sublimation. Sulfur is also recovered from natural gas, coal, crude oil, and other sources, e.g., the flue dusts and gases from the refining of metal sulfide ores. Elemental sulfur is obtained in several forms, including flowers of sulfur, a fine crystalline powder, and roll sulfur (cast cakes or sticks). Elemental sulfur is used in black gunpowder, matches, and fireworks; in the vulcanization of rubber; as a fungicide, insecticide, and fumigant; in the manufacture of phosphate fertilizers; and in the treatment of certain skin diseases. The principal use of sulfur, however, is in the preparation of its compounds. The most important sulfur compound is sulfuric acid. Other important compounds include sulfur dioxide, used as a bleaching agent, disinfectant, and refrigerant; sodium bisulfite, used in paper manufacture; carbon disulfide, an important organic solvent; hydrogen sulfide, sulfur trioxide, and thionyl chloride, used as reagents in chemistry; Epsom salts (magnesium sulfate), used as a laxative, bath additive, exfoliant, and magnesium supplement in plant nutrition; the numerous other sulfate compounds; and sulfa drugs.

The essentials

Description   

Here is a brief description of sulphur.

• Standard state: solid at 298 K
• Colour: lemon yellow
• Classification: Non-metallic
• Availability:

The spelling of sulphur is "sulfur" in the USA and now that IUPAC has decided it has jurisdiction over the British English language (as distinct from American English) as well as nomenclature, so we in the UK are expected to use the f word.

Sulphur is found in meteorites, volcanoes, hot springs, and as galena, gypsum, Epsom salts, and barite. It is recovered commercially from "salt domes" along the Gulf Coast of the USA. Jupiter's moon Io owes its colours to various forms of sulphur. A dark area near the crater Aristarchus on the moon may be a sulphur deposit.

The picture above shows the result from burning a mixture of zinc metal powder and sulphur. Do not attempt this reaction unless are a professionally qualified chemist and you have carried out a legally satisfactory hazard assessment.

Sulphur is a pale yellow, odourless, brittle solid, which is insoluble in water but soluble in carbon disulphide. Sulphur is essential to life. It is a minor constituent of fats, body fluids, and skeletal minerals.

Carbon disulphide, hydrogen sulphide, and sulphur dioxide should be handled extremely carefully. Hydrogen sulphide in very small concentrations can be metabolized, but in higher concentrations it can cause death quickly by respiratory paralysis. It is insidious in that it quickly deadens the sense of smell. Sulphur dioxide is a dangerous component in atmospheric air pollution and is one of the factors responsible for acid rain.

Isolation

It is not normally necessary to make sulphur in the laboratory as it is so readily available. It is found as the native element in nature and extracted by the Frasch process. This is an interesting process since it means that sulphur can be extracted from underground without mining it. In the Frasch process underground deposits of sulphur are forced to the surface using superheated water and steam (160°C, 16 atmospheres, to melt the sulphur) and compressed air (25 atmospheres). This gives molten sulphur which is allowed to cool in large basins. Purity can reach 99.5%.

The process in energy intensive. Commercial success for this operation depends upon suitable geological conditions as well as access to cheap water and energy.

Hydrogen sulphide, H₂S, is an important impurrity in natural gas which must be removed before the gas is used. This is done by an absorption and regeneration process to concentrate the H₂S, followed by a catalytic oxidation (Claus process) using porous catalysts such as Al₂O₃ or Fe₂O₃.

8H₂S + 4O₂ S₈ + 8H₂O

Over the years the Claus process has been improved and a modified process can yield 98% recovery.

In the laboratory, sulphur can be purified by recrystallisation from solutions in carbon disulphide, CS₂. However the resulting crystals are contaminated with solvent, H₂S, and SO₂. One good way to purify sulphur is to use a quartz heater (700°C) immersed in liquid sulphur. Carbon impurities decompose to form volatile materials of solid carbon, which coat the heater. After a week or so, finishing with a distillation under vacuum, the result is sulphur with a carbon content of about 0.0009%.

Sulphur	16 S 32.065(5)

Chemical reactions of the elements

Reaction of sulphur with air

Sulphur burns in air to form the gaseous dioxide sulphur(IV) oxide, SO₂.

S₈(s) + 8O₂(g) 8SO₂(s)

Reaction of sulphur with water

Sulphur does not react with water under normal conditions.

Reaction of sulphur with the halogens

Sulphur racts with all the halogens upon heating. Molten sulphur reacts with molten sulphur to form disulphur dichloride, S₂Cl₂. This apparently smells dreadfully. With excess chlorine and in the presence of a catalyst, such as FeCl₃, Snl₄, etc., it is possible to make a mixture containing an equilibrium mixture of red sulphur(II) chloride, SCl₂, and disulphur dichloride, S₂Cl₂

S₈ + 4Cl₂ 4S₂Cl₂(l) [orange]

S₂Cl₂(l) + Cl₂ 2SCl₂(l) [dark red]

Reaction of sulphur with acids

Sulphur does not react with dilute non-oxidizing acids.

Reaction of sulphur with bases

Sulphur reacts with hot aqueous potassium hydroxide, KOH, to form sulphide and thiosulphate species.

S₈(s) + 6KOH(aq) 2K₂S₃ + K₂S₂O₃ + 3H₂O(l)