K
kainite A naturally occurring double salt of magnesium sulphate and
potassium chloride, MgSO 4 .KCl.3H 2 O.
kalinite A mineral form of *aluminium potassium sulphate
(Al 2 (SO 4 ) 3 .K 2 SO 4 .24H 2 O).
kaolin (china clay) A soft white clay
that is composed chieÛy of the mineral kaolinite (see clay minerals). It is
formed during the weathering and
hydrothermal alteration of other
clays or feldspar. Kaolin is mined in
the UK, France, the Czech Republic,
and USA. Besides its vital importance
in the ceramics industry it is also
used extensively as a Üller in the
manufacture of rubber, paper, paint,
and textiles and as a constituent of
medicines.
Kastle Meyer test (phenolphthalein test) A presumptive test used
to indicate blood. Phenolphthalein
and hydrogen peroxide are used; reaction with haemoglobin in the
blood gives a pink colour.
katharometer An instrument for
comparing the thermal conductivities of two gases by comparing the
rate of loss of heat from two heating
coils surrounded by the gases. The instrument can be used to detect the
presence of a small amount of an impurity in air and is also used as a detector in gas chromatography.
Kekulé, Friedrich August von
Stradonitz (1829–96) German
chemist, who became professor at
Ghent (1858) and later at Bonn
(1867). He studied the structures of
organic molecules and was the Ürst
to recognise that carbon atoms form
stable chains. Kekulé is best remembered for his proposed structure for
{benzene} in 1865, which he correctly interpreted as having a symmetrical ring of six carbon atoms.
Kekulé structure A proposed
structure of *benzene in which the
molecule has a hexagonal ring of carbon atoms linked by alternating double and single bonds. Kekulé
structures contribute to the resonance hybrid of benzene. The structure was suggested in 1865 by
Friedrich August *Kekulé.
kelvin Symbol K. The *SI unit of
thermodynamic *temperature equal
to the fraction 1/273.16 of the thermodynamic temperature of the
*triple point of water. The magnitude of the kelvin is equal to that of
the degree Celsius (centigrade), but a
temperature expressed in degrees
celsius is numerically equal to the
temperature in kelvins less 273.15
(i.e. °C = K – 273.15). The *absolute
zero of temperature has a temperature of 0 K (–273.15°C). The former
name degree kelvin (symbol °K) became obsolete by international agreement in 1967. The unit is named
after Lord Kelvin.
Kelvin, Lord (William Thomson;
1824–1907) British physicist, born in
Belfast, who became professor of
natural philosophy at Glasgow University in 1846. He carried out important experimental work on
electromagnetism, inventing the
mirror galvanometer and contributing to the development of telegraphy. He also worked with James
*Joule on the *Joule–Thomson (or
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kainite A naturally occurring double salt of magnesium sulphate and
potassium chloride, MgSO 4 .KCl.3H 2 O.
kalinite A mineral form of *aluminium potassium sulphate
(Al 2 (SO 4 ) 3 .K 2 SO 4 .24H 2 O).
kaolin (china clay) A soft white clay
that is composed chieÛy of the mineral kaolinite (see clay minerals). It is
formed during the weathering and
hydrothermal alteration of other
clays or feldspar. Kaolin is mined in
the UK, France, the Czech Republic,
and USA. Besides its vital importance
in the ceramics industry it is also
used extensively as a Üller in the
manufacture of rubber, paper, paint,
and textiles and as a constituent of
medicines.
Kastle Meyer test (phenolphthalein test) A presumptive test used
to indicate blood. Phenolphthalein
and hydrogen peroxide are used; reaction with haemoglobin in the
blood gives a pink colour.
katharometer An instrument for
comparing the thermal conductivities of two gases by comparing the
rate of loss of heat from two heating
coils surrounded by the gases. The instrument can be used to detect the
presence of a small amount of an impurity in air and is also used as a detector in gas chromatography.
Kekulé, Friedrich August von
Stradonitz (1829–96) German
chemist, who became professor at
Ghent (1858) and later at Bonn
(1867). He studied the structures of
organic molecules and was the Ürst
to recognise that carbon atoms form
stable chains. Kekulé is best remembered for his proposed structure for
{benzene} in 1865, which he correctly interpreted as having a symmetrical ring of six carbon atoms.
Kekulé structure A proposed
structure of *benzene in which the
molecule has a hexagonal ring of carbon atoms linked by alternating double and single bonds. Kekulé
structures contribute to the resonance hybrid of benzene. The structure was suggested in 1865 by
Friedrich August *Kekulé.
kelvin Symbol K. The *SI unit of
thermodynamic *temperature equal
to the fraction 1/273.16 of the thermodynamic temperature of the
*triple point of water. The magnitude of the kelvin is equal to that of
the degree Celsius (centigrade), but a
temperature expressed in degrees
celsius is numerically equal to the
temperature in kelvins less 273.15
(i.e. °C = K – 273.15). The *absolute
zero of temperature has a temperature of 0 K (–273.15°C). The former
name degree kelvin (symbol °K) became obsolete by international agreement in 1967. The unit is named
after Lord Kelvin.
Kelvin, Lord (William Thomson;
1824–1907) British physicist, born in
Belfast, who became professor of
natural philosophy at Glasgow University in 1846. He carried out important experimental work on
electromagnetism, inventing the
mirror galvanometer and contributing to the development of telegraphy. He also worked with James
*Joule on the *Joule–Thomson (or
www.AzShimi.ir www.AzShimi.com