solves in water to give *carbonic
acid.
Large quantities of solid carbon
dioxide (dry ice) are used in processes
requiring large-scale refrigeration. It
is also used in Üre extinguishers as a
desirable alternative to water for
most Üres, and as a constituent of
medical gases as it promotes exhalation. It is also used in carbonated
drinks.
The level of carbon dioxide in the
atmosphere has increased by some
12% in the last 100 years, mainly because of extensive burning of fossil
fuels and the destruction of large
areas of rain forest. This has been
postulated as the main cause of the
average increase of 0.5°C in global
temperatures over the same period,
through the *greenhouse effect.
Steps are now being taken to prevent
further increases in atmospheric CO 2
concentration and subsequent global
warming.
carbon disulphide (carbon bisulphide) A colourless highly refractive
liquid, CS 2 , slightly soluble in water
and soluble in ethanol and ether; r.d.
1.261; m.p. –110°C; b.p. 46.3°C. Pure
carbon disulphide has an ethereal
odour but the commercial product is
contaminated with a variety of other
sulphur compounds and has a most
unpleasant smell. It was previously
manufactured by heating a mixture
of wood, sulphur, and charcoal; modern processes use natural gas and sulphur. Carbon disulphide is an
excellent solvent for oils, waxes, rubber, sulphur, and phosphorus, but its
use is decreasing because of its high
toxicity and its Ûammability. It is
used for the preparation of xanthates
in the manufacture of viscose yarns.
carbon Übres Fibres of carbon in
which the carbon has an oriented
crystal structure. Carbon Übres are
made by heating textile Übres and
are used in strong composite materials for use at high temperatures.
carbonic acid A dibasic acid,
H 2 CO 3 , formed in solution when carbon dioxide is dissolved in water:
CO 2 (aq) + H 2 O(l) ˆ H 2 CO 3 (aq)
The acid is in equilibrium with dissolved carbon dioxide, and also dissociates as follows:
H 2 CO 3 ˆ H
+ + HCO 3
–
K a = 4.5 × 10
–7 mol dm
–3
HCO 3
–
ˆ CO 3
2– + H
+
K a = 4.8 × 10
–11 mol dm
–3
The pure acid cannot be isolated,
although it can be produced in ether
solution at –30°C. Carbonic acid gives
rise to two series of salts: the *carbonates and the *hydrogencarbonates.
carbonium ion See carbocation.
carbonize (carburize) To change an
organic compound into carbon by
heating, or to coat something with
carbon in this way.
carbon monoxide A colourless
odourless gas, CO, sparingly soluble
in water and soluble in ethanol and
benzene; d. 1.25 g dm
–3 (0°C); m.p.
–199°C; b.p. –191.5°C. It is Ûammable
and highly toxic. In the laboratory it
can be made by the dehydration of
methanoic acid (formic acid) using
concentrated sulphuric acid. Industrially it is produced by the oxidation of
natural gas (methane) or (formerly)
by the water-gas reaction. It is
formed by the incomplete combustion of carbon and is present in carexhaust gases.
It is a neutral oxide, which burns
in air to give carbon dioxide, and is a
good reducing agent, used in a number of metallurgical processes. It has
the interesting chemical property
of forming a range of transition
metal carbonyls, e.g. Ni(CO) 4 . Carbon monoxide is able to use vacant
carbon disulphide
102
c
www.AzShimi.ir www.AzShimi.com
acid.
Large quantities of solid carbon
dioxide (dry ice) are used in processes
requiring large-scale refrigeration. It
is also used in Üre extinguishers as a
desirable alternative to water for
most Üres, and as a constituent of
medical gases as it promotes exhalation. It is also used in carbonated
drinks.
The level of carbon dioxide in the
atmosphere has increased by some
12% in the last 100 years, mainly because of extensive burning of fossil
fuels and the destruction of large
areas of rain forest. This has been
postulated as the main cause of the
average increase of 0.5°C in global
temperatures over the same period,
through the *greenhouse effect.
Steps are now being taken to prevent
further increases in atmospheric CO 2
concentration and subsequent global
warming.
carbon disulphide (carbon bisulphide) A colourless highly refractive
liquid, CS 2 , slightly soluble in water
and soluble in ethanol and ether; r.d.
1.261; m.p. –110°C; b.p. 46.3°C. Pure
carbon disulphide has an ethereal
odour but the commercial product is
contaminated with a variety of other
sulphur compounds and has a most
unpleasant smell. It was previously
manufactured by heating a mixture
of wood, sulphur, and charcoal; modern processes use natural gas and sulphur. Carbon disulphide is an
excellent solvent for oils, waxes, rubber, sulphur, and phosphorus, but its
use is decreasing because of its high
toxicity and its Ûammability. It is
used for the preparation of xanthates
in the manufacture of viscose yarns.
carbon Übres Fibres of carbon in
which the carbon has an oriented
crystal structure. Carbon Übres are
made by heating textile Übres and
are used in strong composite materials for use at high temperatures.
carbonic acid A dibasic acid,
H 2 CO 3 , formed in solution when carbon dioxide is dissolved in water:
CO 2 (aq) + H 2 O(l) ˆ H 2 CO 3 (aq)
The acid is in equilibrium with dissolved carbon dioxide, and also dissociates as follows:
H 2 CO 3 ˆ H
+ + HCO 3
–
K a = 4.5 × 10
–7 mol dm
–3
HCO 3
–
ˆ CO 3
2– + H
+
K a = 4.8 × 10
–11 mol dm
–3
The pure acid cannot be isolated,
although it can be produced in ether
solution at –30°C. Carbonic acid gives
rise to two series of salts: the *carbonates and the *hydrogencarbonates.
carbonium ion See carbocation.
carbonize (carburize) To change an
organic compound into carbon by
heating, or to coat something with
carbon in this way.
carbon monoxide A colourless
odourless gas, CO, sparingly soluble
in water and soluble in ethanol and
benzene; d. 1.25 g dm
–3 (0°C); m.p.
–199°C; b.p. –191.5°C. It is Ûammable
and highly toxic. In the laboratory it
can be made by the dehydration of
methanoic acid (formic acid) using
concentrated sulphuric acid. Industrially it is produced by the oxidation of
natural gas (methane) or (formerly)
by the water-gas reaction. It is
formed by the incomplete combustion of carbon and is present in carexhaust gases.
It is a neutral oxide, which burns
in air to give carbon dioxide, and is a
good reducing agent, used in a number of metallurgical processes. It has
the interesting chemical property
of forming a range of transition
metal carbonyls, e.g. Ni(CO) 4 . Carbon monoxide is able to use vacant
carbon disulphide
102
c
www.AzShimi.ir www.AzShimi.com