soda ashAnhydrous *sodium car-
bonate, Na 2 CO 3.
soda limeA mixed hydroxide of
sodium and calcium made by slaking
lime with caustic soda solution (to
give NaOH + Ca(OH) 2 ) and recovering
greyish white granules by evapora-
tion. The material is produced largely
for industrial adsorption of carbon
dioxide and water, but alsoÜnds
some applications in pollution and
efÛuent control. It is also used as a
laboratory drying agent.
sodamideSee sodium amide.
Soddy, Frederick (1877–1956)
British chemist, who worked with
Ernest Rutherford in Canada and
William Ramsay in London before
Ünally settling in Oxford in 1919. His
announcement in 1913 of the exis-
tence of *isotopes won him the 1921
Nobel Prize for physics.
sodiumSymbol Na. A soft silvery
reactive element belonging to group
1 (formerly IA) of the periodic table
(see alkali metals); a.n. 11; r.a.m.
22.9898; r.d. 0.97; m.p. 97.8°C; b.p.
882–889°C. Sodium occurs as the
chloride in sea water and in the min-
eral halite. It is extracted by electrol-
ysis in a Downs cell. The metal is
used as a reducing agent in certain
reactions and liquid sodium is also a
coolant in nuclear reactors. Chemi-
cally, it is highly reactive, oxidizing
in air and reacting violently with
water (it is kept under oil). It dis-
solves in liquid ammonia to form
blue solutions containing solvated
electrons. Sodium is a major *essen-
tial element required by living organ-
isms. The element wasÜrst isolated
by Humphry Davy in 1807.
A
- Information from the WebElements site
sodium acetateSee sodium
ethanoate.
sodium aluminateA white solid,
NaA1O 2 or Na 2 Al 2 O 4 , which is in-
soluble in ethanol and soluble in
water giving strongly alkaline solu-
tions; m.p. 1800°C. It is manufac-
tured by heating bauxite with
sodium carbonate and extracting
the residue with water, or it may be
prepared in the laboratory by adding
excess aluminium to hot concen-
trated sodium hydroxide. In solu-
tion the ion Al(OH) 4 – predominates.
Sodium aluminate is used as a
mordant, in the production of zeo-
lites, in efÛuent treatment, in glass
manufacture, and in cleansing com-
pounds.
sodium amide (sodamide)A white
crystalline powder, NaNH 2 , which de-
composes in water and in warm
ethanol, and has an odour of ammo-
nia; m.p. 210°C; b.p. 400°C. It is pro-
duced by passing dry ammonia over
metallic sodium at 350°C. It reacts
with red-hot carbon to give sodium
cyanide and with nitrogen(I) oxide to
give sodium azide.sodium azideA white or colour-
less crystalline solid, NaN 3 , soluble in
water and slightly soluble in alcohol;
hexagonal; r.d. 1.846; decomposes on
heating. It is made by the action of
nitrogen(I) oxide on hot sodamide
(NaNH 2 ) and is used as an organic
reagent and in the manufacture of
detonators.sodium benzenecarboxylate
(sodium benzoate)An either colour-
less crystalline or white amorphous
powder, C 6 H 5 COONa, soluble in
water and slightly soluble in ethanol.
It is made by the reaction of sodium
hydroxide with benzoic acid and is
used in the dyestuffs industry and as
a food preservative. It was formerly
used as an antiseptic.
sodium benzoateSee sodium ben-
zenecarboxylate.487 sodium benzoate
s