Stokes lines being called the S-branch
of the Raman spectrum.
Stokes radiation is named after the
British physicist Sir George Gabriel
Stokes (1819–1903).
stopped-Ûow technique A technique for investigating fast reactions
in solution. The reactant solutions
are rapidly mixed and Ûow through a
tube. The composition or properties
of the mixture are monitored at
some point in the tube (e.g. by photometry). The Ûow is suddenly
stopped and the change of signal
with time is used to elucidate the kinetics of the process. The stoppedÛow technique is useful for reactions
occurring in the millisecond time
range.
s.t.p. Standard temperature and
pressure, formerly known as N.T.P.
(normal temperature and pressure).
The standard conditions used as a
basis for calculations involving quantities that vary with temperature and
pressure. These conditions are used
when comparing the properties of
gases. They are 273.15 K (or 0°C) and
101 325 Pa (or 760.0 mmHg).
straight chain See chain.
strange attractor See attractor.
streaming potential A potential
difference that occurs when a liquid
under pressure is forced through a
narrow opening or diaphragm. It can
be measured between two electrodes
at each end of a capillary tube made
of the same material as the diaphragm.
strong acid An *acid that is completely dissociated in aqueous solution.
strontia See strontium oxide.
strontianite A mineral form of
*strontium carbonate, SrCO 3 .
strontium Symbol Sr. A soft yellowish metallic element belonging to
group 2 (formerly IIA) of the periodic
table (see alkaline-earth metals);
a.n. 38; r.a.m. 87.62; r.d. 2.6; m.p.
769°C; b.p. 1384°C. The element is
found in the minerals strontianite
(SrCO 3 ) and celestine (SrSO 4 ). It can
be obtained by roasting the ore to
give the oxide, followed by reduction
with aluminium (i.e. the *Goldschmidt process). The element,
which is highly reactive, is used in
certain alloys and as a vacuum getter.
The isotope strontium–90 is present
in radioactive fallout (half-life 28
years), and can be metabolized with
calcium so that it collects in bone.
Strontium was discovered by Martin
Klaproth (1743–1817) and Thomas
Hope (1766–1844) in 1798 and isolated by Humphry Davy in 1808.
A
• Information from the WebElements site
strontium bicarbonate See strontium hydrogencarbonate.
strontium carbonate A white
solid, SrCO 3 ; orthorhombic; r.d. 3.7;
decomposes at 1340°C. It occurs naturally as the mineral strontianite and
is prepared industrially by boiling celestine (strontium sulphate) with ammonium carbonate. It can also be
prepared by passing carbon dioxide
over strontium oxide or hydroxide or
by passing the gas through a solution
of strontium salt. It is a phosphor,
used to coat the glass of cathode-ray
screens, and is also used in the reÜning of sugar, as a slagging agent in
certain metal furnaces, and to provide a red Ûame in Üreworks.
strontium chloride A white compound, SrCl 2 . The anhydrous salt
(cubic; r.d. 3.05; m.p. 872°C; b.p.
1250°C) can be prepared by passing
chlorine over heated strontium. It is
deliquescent and readily forms the
hexahydrate, SrCl 2 .6H 2 O (r.d. 2.67).
stopped-Ûow technique
506
s
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of the Raman spectrum.
Stokes radiation is named after the
British physicist Sir George Gabriel
Stokes (1819–1903).
stopped-Ûow technique A technique for investigating fast reactions
in solution. The reactant solutions
are rapidly mixed and Ûow through a
tube. The composition or properties
of the mixture are monitored at
some point in the tube (e.g. by photometry). The Ûow is suddenly
stopped and the change of signal
with time is used to elucidate the kinetics of the process. The stoppedÛow technique is useful for reactions
occurring in the millisecond time
range.
s.t.p. Standard temperature and
pressure, formerly known as N.T.P.
(normal temperature and pressure).
The standard conditions used as a
basis for calculations involving quantities that vary with temperature and
pressure. These conditions are used
when comparing the properties of
gases. They are 273.15 K (or 0°C) and
101 325 Pa (or 760.0 mmHg).
straight chain See chain.
strange attractor See attractor.
streaming potential A potential
difference that occurs when a liquid
under pressure is forced through a
narrow opening or diaphragm. It can
be measured between two electrodes
at each end of a capillary tube made
of the same material as the diaphragm.
strong acid An *acid that is completely dissociated in aqueous solution.
strontia See strontium oxide.
strontianite A mineral form of
*strontium carbonate, SrCO 3 .
strontium Symbol Sr. A soft yellowish metallic element belonging to
group 2 (formerly IIA) of the periodic
table (see alkaline-earth metals);
a.n. 38; r.a.m. 87.62; r.d. 2.6; m.p.
769°C; b.p. 1384°C. The element is
found in the minerals strontianite
(SrCO 3 ) and celestine (SrSO 4 ). It can
be obtained by roasting the ore to
give the oxide, followed by reduction
with aluminium (i.e. the *Goldschmidt process). The element,
which is highly reactive, is used in
certain alloys and as a vacuum getter.
The isotope strontium–90 is present
in radioactive fallout (half-life 28
years), and can be metabolized with
calcium so that it collects in bone.
Strontium was discovered by Martin
Klaproth (1743–1817) and Thomas
Hope (1766–1844) in 1798 and isolated by Humphry Davy in 1808.
A
• Information from the WebElements site
strontium bicarbonate See strontium hydrogencarbonate.
strontium carbonate A white
solid, SrCO 3 ; orthorhombic; r.d. 3.7;
decomposes at 1340°C. It occurs naturally as the mineral strontianite and
is prepared industrially by boiling celestine (strontium sulphate) with ammonium carbonate. It can also be
prepared by passing carbon dioxide
over strontium oxide or hydroxide or
by passing the gas through a solution
of strontium salt. It is a phosphor,
used to coat the glass of cathode-ray
screens, and is also used in the reÜning of sugar, as a slagging agent in
certain metal furnaces, and to provide a red Ûame in Üreworks.
strontium chloride A white compound, SrCl 2 . The anhydrous salt
(cubic; r.d. 3.05; m.p. 872°C; b.p.
1250°C) can be prepared by passing
chlorine over heated strontium. It is
deliquescent and readily forms the
hexahydrate, SrCl 2 .6H 2 O (r.d. 2.67).
stopped-Ûow technique
506
s
www.AzShimi.ir www.AzShimi.com