Sulphur, S, is a yellow nonmetallic main group element belonging to the
of the periodic table.
Although sulphur is in the same group in the periodic table as oxygen,
there are more differences in the chemical characteristics of
these elements than there are similarities. Thus, while oxygen
always displays a valency of two, sulphur displays valences of
four (in sulphur dioxide, SO2), six (in thionyl chloride, socl2) and
eight (in sulphur hexafluoride, SF8).
- Atomic Number : 16
- Relative Atomic Mass : 32.06
- Melting Point : 112.8 degC
- Boiling Point : 444.667 degC
- Relative Density : 2.07
In the elemental state, sulphur exists in polymeric forms.
Sulphur is an essential element for living organisms, and is present
in some amino-acids.
- Sulphur has been known since the beginning of history, and is
described in the Bible.
- Sulphur has been used by the Greeks and Romans as a fumigant
- Sulphur is widely distributed as the free element and combined
- Sulphur is found near volcanoes, where it is formed by the
reaction of sulphur dioxide and hydrogen sulphide which are
associated with the volcanoes.
- Sulphur also occurs in many metal ores, including
- gelena, PbS,
- zinc blende, ZnS,
- cinnebar, HgS,
- stibnite, Sb2S3,
- copper pyrites, Cu2S.Fe2S3, and
- iron pyrites, Fe2S.
- The important sulphate ores include
- gypsum, CaSO4, and
- heavy spar, BaSO4.
- Sulphur is separated from the minerals in its ores by heating,
when the liquid sulphur drains from the ore body. Normally, part
of the sulphur in the ore is burned and the heat used to melt
the remaining sulphur so that it leaches from the hot mass.
This extraction procedure called the Gill Process, and it is
widely used in Sicily.
- Sulphur is extracted from underground ore bodies in the
United States using the Frasch Process, where superheated water
is pumped underground to melt the sulphur which is then forces
to the surface.
Sulphur occurs in a large number of allotropic forms in the solid state.
Several liquid forms are also known.
Rhombic Sulphur which is also known as Octahedral Sulphur or
alpha-Sulphur, is a yellow crystalline solid, which crystallises
from a solution in carbon disulphide. X-ray investigation shows
this form to consist of eight sulphur atoms in the molecule in a
Monoclinic Sulphur which is also known as Prismatic Sulphur
or beta-Sulphur, is a yellow crystalline solid, which is obtained
by allowing molten sulphur to solidify, when long prismatic needles
form on the walls of the container that can be separated from
the still molten liquid by pouring off the latter. X-ray
investigation shows this form to consist of eight sulphur atoms
in the molecule in a ring structure, but arranged within the
crystal in a different manner to that in rhombic sulphur.
Plastic Sulphur which is also known as gamma-Sulphur, is a
tough elastic substance that is formed when molten sulphur
is poured into cold water. On standing it slowly
Amorphous Sulphur is the insoluble white amorphous solid that
remains when flowers of sulphur are extracted with carbon disulphide.
Colloidal Sulphur which is also known as delta-Sulphur, is a
yellow crystalline solid.
Sulphur is an important industrial raw material which is used
- in the manufacture of sulphuric acid,
- in the manufacture of sulphur dioxide and sodium sulphite
which are used for bleaching straw and wood fibers, and for
removing lignin from wood pulp for the paper industry, and
- in the manufacture of organic chemicals which contain sulphur.
Start of Hypertext ....
Hypertext Copyright (c) 2000 Donal O'Leary. All Rights Reserved.