mals (see essential element). ArtiÜcially produced cobalt–60 is an important radioactive tracer and
cancer-treatment agent. The element
was discovered by Georg Brandt
(1694–1768) in 1737.
A
• Information from the WebElements site
cobalt(II) oxide A pink solid, CoO;
cubic; r.d. 6.45; m.p. 1935°C. The addition of potassium hydroxide to a
solution of cobalt(II) nitrate gives a
bluish-violet precipitate, which on
boiling is converted to pink impure
cobalt(II) hydroxide. On heating this
in the absence of air, cobalt(II) oxide
is formed. The compound is readily
oxidized in air to form tricobalt
tetroxide, Co 3 O 4 , and is readily reduced by hydrogen to the metal.
cobalt(III) oxide (cobalt sesquioxide) A black grey insoluble solid,
Co 2 O 3 ; hexagonal or rhombic; r.d.
5.18; decomposes at 895°C. It is produced by the ignition of cobalt nitrate; the product however never has
the composition corresponding exactly to cobalt(III) oxide. On heating
it readily forms Co 3 O 4 , which contains both Co(II) and Co(III), and is
easily reduced to the metal by hydrogen. Cobalt(III) oxide dissolves in
strong acid to give unstable brown
solutions of trivalent cobalt salts.
With dilute acids cobalt(II) salts are
formed.
cobalt steel Any of a group of
alloy *steels containing 5–12% of
cobalt, 14–20% of tungsten, usually
with 4% of chromium and 1–2% of
vanadium. They are very hard but
somewhat brittle. Their main use is
in high-speed tools.
cobalt thiocyanate test See
scott’s test.
cocaine A powerful drug present in
the leaver of the coca plant (Erythroxylon coca). It stimulates the central
nervous system and has effects similar to the amphetamines. It was originally used as a local anaesthetic. The
illegal drug is usually the soluble hydrochloride. This can be converted
into the free-base form (known as
crack cocaine) by dissolving in water
and heating with sodium bicarbonate. Cocaine is a class A drug in the
UK. It can be detected by *Scott’s
test.
cobalt(II) oxide
132
c
N
O
O
O
O
CH 3
CH 3
Cocaine
cocurrent Ûow Flow of two Ûuids
in the same direction with transfer of
matter or heat between them. Compare countercurrent flow.
codeine An alkaloid C 18 H 21 NO 3
found in opium. It is structurally similar to morphine, from which it is
produced, and is used in the form of
the sulphate or phosphate as a
painkiller and cough medicine.
Codeine is converted into morphine
in the liver. It is used to some extent
as a recreational drug. In the UK it is
a class B drug but can be obtained in
composite over-the-counter preparations in which it has a low concentration and is combined with paracetamol or ibuprofen. See also opioids.
coenzyme An organic nonprotein
molecule that associates with an
enzyme molecule in catalysing biochemical reactions. Coenzymes usually participate in the substrate–
enzyme interaction by donating or
accepting certain chemical groups.
www.AzShimi.ir www.AzShimi.com
cancer-treatment agent. The element
was discovered by Georg Brandt
(1694–1768) in 1737.
A
• Information from the WebElements site
cobalt(II) oxide A pink solid, CoO;
cubic; r.d. 6.45; m.p. 1935°C. The addition of potassium hydroxide to a
solution of cobalt(II) nitrate gives a
bluish-violet precipitate, which on
boiling is converted to pink impure
cobalt(II) hydroxide. On heating this
in the absence of air, cobalt(II) oxide
is formed. The compound is readily
oxidized in air to form tricobalt
tetroxide, Co 3 O 4 , and is readily reduced by hydrogen to the metal.
cobalt(III) oxide (cobalt sesquioxide) A black grey insoluble solid,
Co 2 O 3 ; hexagonal or rhombic; r.d.
5.18; decomposes at 895°C. It is produced by the ignition of cobalt nitrate; the product however never has
the composition corresponding exactly to cobalt(III) oxide. On heating
it readily forms Co 3 O 4 , which contains both Co(II) and Co(III), and is
easily reduced to the metal by hydrogen. Cobalt(III) oxide dissolves in
strong acid to give unstable brown
solutions of trivalent cobalt salts.
With dilute acids cobalt(II) salts are
formed.
cobalt steel Any of a group of
alloy *steels containing 5–12% of
cobalt, 14–20% of tungsten, usually
with 4% of chromium and 1–2% of
vanadium. They are very hard but
somewhat brittle. Their main use is
in high-speed tools.
cobalt thiocyanate test See
scott’s test.
cocaine A powerful drug present in
the leaver of the coca plant (Erythroxylon coca). It stimulates the central
nervous system and has effects similar to the amphetamines. It was originally used as a local anaesthetic. The
illegal drug is usually the soluble hydrochloride. This can be converted
into the free-base form (known as
crack cocaine) by dissolving in water
and heating with sodium bicarbonate. Cocaine is a class A drug in the
UK. It can be detected by *Scott’s
test.
cobalt(II) oxide
132
c
N
O
O
O
O
CH 3
CH 3
Cocaine
cocurrent Ûow Flow of two Ûuids
in the same direction with transfer of
matter or heat between them. Compare countercurrent flow.
codeine An alkaloid C 18 H 21 NO 3
found in opium. It is structurally similar to morphine, from which it is
produced, and is used in the form of
the sulphate or phosphate as a
painkiller and cough medicine.
Codeine is converted into morphine
in the liver. It is used to some extent
as a recreational drug. In the UK it is
a class B drug but can be obtained in
composite over-the-counter preparations in which it has a low concentration and is combined with paracetamol or ibuprofen. See also opioids.
coenzyme An organic nonprotein
molecule that associates with an
enzyme molecule in catalysing biochemical reactions. Coenzymes usually participate in the substrate–
enzyme interaction by donating or
accepting certain chemical groups.
www.AzShimi.ir www.AzShimi.com