sulfur ing.docx

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SULFUR

Sulfur: the essentials

Sulphur (sulfur) 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.

The spelling of sulphur is "sulfur" in the USA while sulphur is common elsewhere.

IUPAC has does not have jurisdiction over language but has decided sulfur is preferred.

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. 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.

Table: basic information about and classifications of sulfur.

Name: Sulfur Symbol: S Atomic number: 16 Atomic weight: 32.065 (5) Standard state: solid at 298 K CAS Registry ID: 7704-34-9

Group in periodic table: 16 Group name: Chalcogen Period in periodic table: 3 Block in periodic table: p-block Colour: lemon yellow Classification: Non-metallic
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The picture above shows the result from burning a mixture of zinc metal powder and sulphur.

Sulfur: historical information

Sulfur was discoveredby Known since ancient times at no data in not known. Origin

of name: from the Sanskrit word "sulvere" meaning "sulphur"; also from the Latin word

"sulphurium" meaning "sulphur".

Sulphur was known in ancient times and referred to in Genesis as brimstone. Assyrian

texts dated around 700-600 BC refer to it as the "product of the riverside", where deposits

could be found. In the 9th century BC, Homer mentioned "pest-averting sulphur". In 424 BC,

the tribe of Bootier destroyed a city's walls using a burning mixture of coal, sulphur, and tar.

Around the 12th century, the Chinese, probably, discovered gun powder (a mixture of

potassium nitrate, KNO3, carbon, and sulphur).

Sulphur is one of the elements which has an alchemical symbol, shown below (alchemy is an

ancient pursuit concerned with, for instance, the transformation of other metals into

gold). Alchemists knew that mercury can be fixed with sulphur. Possibly Antoine

Lavoisier should be credited with convincing the scientific community that sulphur

is an element (around 1777).

Sometime prior to the autumn of 1803, the Englishman John Dalton was able to

explain the results of some of his studies by assuming that matter is composed of atoms and

that all samples of any given compound consist of the same combination of these atoms.

Dalton also noted that in series of compounds, the ratios of the masses of the second element

that combine with a given weight of the first element can be reduced to small whole numbers

(the law of multiple proportions). This was further evidence for atoms. Dalton's theory of

atoms was published by Thomas Thomson in the 3rd edition of his System of Chemistry in

1807 and in a paper about strontium oxalates published in the Philosophical Transactions.
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Dalton published these ideas himself in the following year in the New System of Chemical

Philosophy. The symbol used by Dalton for sulphur is shown below. [See History of

Chemistry, Sir Edward Thorpe, volume 1, Watts & Co, London, 1914.]

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Isolation

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 (160C, 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 (700C) 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 sulphurwith a carbon content of about 0.0009%.
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Chemical reactions of the elements

1. Reaction of sulfur with air

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

S8(s) + 8O2(g) 8SO2(g)

2. Reaction of sulfur with water

Sulphur does not react with water under normal conditions.

3. Reaction of sulfur with the halogens

Sulphur racts with all the halogens upon heating. Sulphur reacts with fluorine, F 2, and

burns to form the hexafluoride sulphur(VI) fluoride.

S8(s) + 24F2(g) 8SF6(l) [orange]

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, suchas 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]

4. Reaction of sulfur with acids

Sulphur does not react with dilute non-oxidizing acids.

5. Reaction of sulfur with bases

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

thiosulphate species.

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

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