mals (see essential element). ArtiÜ-
cially produced cobalt–60 is an im-
portant 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) oxideA pink solid, CoO;
cubic; r.d. 6.45; m.p. 1935°C. The ad-
dition 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 re-
duced by hydrogen to the metal.cobalt(III) oxide (cobalt sesquiox-
ide)A black grey insoluble solid,
Co 2 O 3 ; hexagonal or rhombic; r.d.
5.18; decomposes at 895°C. It is pro-
duced by the ignition of cobalt ni-
trate; the product however never has
the composition corresponding ex-
actly to cobalt(III) oxide. On heating
it readily forms Co 3 O 4 , which con-
tains both Co(II) and Co(III), and is
easily reduced to the metal by hydro-
gen. 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 steelAny 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 testSee
scott’s test.cocaineA powerful drug present in
the leaver of the coca plant (Eryth-roxylon coca). It stimulates the central
nervous system and has effects simi-
lar to the amphetamines. It was origi-
nally used as a local anaesthetic. The
illegal drug is usually the soluble hy-
drochloride. This can be converted
into the free-base form (known as
crack cocaine) by dissolving in water
and heating with sodium bicarbon-
ate. Cocaine is a class A drug in the
UK. It can be detected by *Scott’s
test.cobalt(II) oxide 132c
N
OOOOCH 3CH 3Cocainecocurrent ÛowFlow of twoÛuids
in the same direction with transfer of
matter or heat between them. Com-
pare countercurrent flow.
codeineAn alkaloid C 18 H 21 NO 3
found in opium. It is structurally sim-
ilar 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 prepara-
tions in which it has a low concentra-
tion and is combined with paraceta-
mol or ibuprofen. See also opioids.coenzymeAn organic nonprotein
molecule that associates with an
enzyme molecule in catalysing bio-
chemical reactions. Coenzymes usu-
ally participate in the substrate–
enzyme interaction by donating or
accepting certain chemical groups.