Sodium

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Sodium
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Properties, occurrence, and uses. Sodium is a
very soft, silvery-white metal. It occurs
abundantly in nature in compounds, especially
common salt sodium chloride (NaCl)which forms
the mineral halite and comprises about 80 percent
of the dissolved constituents of seawater. Sir
Humphry Davy first prepared sodium in its
elemental form (1807) by the electrolysis of
fused sodium hydroxide (NaOH). Sodium is the most
common alkali metal and the sixth most abundant
element on Earth, comprising 2.8 percent of the
Earth's crust it also occurs in more than trace
amounts in the stars and Sun. Lighter than water,
it can be cut with a knife at room temperature
and is brittle at low temperatures. It conducts
heat and electricity easily and exhibits to a
marked degree the photoelectric effect (emission
of electrons when exposed to light). Sodium
reacts vigorously with water to give hydrogen
(which may ignite from the heat of the reaction)
and sodium hydroxide. The metal is extremely
active chemically, easily unites with oxygen of
the air, and usually must be kept immersed in an
inert atmosphere such as nitrogen or in inert
liquids such as kerosene or naphtha. Because
sodium is so reactive, it never occurs in the
free state in nature. It is commercially produced
by electrolyzing sodium chloride.
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Kerosene is a complex mixture of hydrocarbons
from a variety of chemical processes blended to
meet standardized product specifications.
Composition varies greatly and includes C9 to C16
hydrocarbons with a boiling range of about
300-550 degrees Fahrenheit
A petroleum distillate, from the same "middle
distillates" as kerosene and "mineral spirits",
but is somewhat more volatile than kerosene.
Naphtha is the "first cut", coming off in
fractional distillation BEFORE Kerosene. Today
used as a solvent, and paint thinner (not
recommended as such!). Has been sold in a blended
form by Coleman as "white gas" or "Coleman Fuel"
for years.
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Inexpensive and available in tank-car quantities,
sodium is widely used in the manufacture of
chemicals and pharmaceuticals, in metallurgy, as
a heat exchanger in atomic reactors and certain
types of engines, and in sodium vapour lamps.
Natural sodium is the stable isotope of mass 23.
Of the six radioactive, artificial isotopes,
sodium-22 (2.6-year half-life) is used as a
radioactive tracer for natural sodium, sodium-24
(15-hour half-life) is limited in use by its
short life, and the rest have half-lives of a
minute or less. The yellow colour of the sodium
vapour lamp and the sodium flame (the basis of an
analytical test for sodium) is identified with
two prominent lines in the yellow portion of the
light spectrum.
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Principal compounds. Sodium is highly reactive,
forming a wide variety of compounds with nearly
all inorganic and organic anions. It has a
valence of 1, and its single valence electron is
lost with great ease, yielding the colourless
sodium ion (Na).
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Sodium hydroxide (NaOH) is a corrosive, white
crystalline solid that readily absorbs moisture
until it liquefies. Commonly called caustic soda,
or lye, sodium hydroxide is the most widely used
industrial alkali. It is highly corrosive to
animal and vegetable tissue. The alkaline
solutions it forms when dissolved in water
neutralize acids in various commercial processes
in petroleum refining, it removes sulfuric and
organic acids in soapmaking, it reacts with
fatty acids. In the making of cellophane, paper,
viscose rayon, and other products, its alkaline
solutions enter into the treatment of cellulose
and into the manufacture of many chemicals.
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The most important and familiar sodium compound
is sodium chloride, or common salt, NaCl. Most
other sodium compounds are prepared either
directly or indirectly from sodium chloride,
which occurs in seawater, in natural brines, and
as rock salt. Other major commercial applications
of sodium chloride include its use in the
manufacture of chlorine and sodium hydroxide by
electrolytic decomposition and in the production
of sodium carbonate (Na2CO3) by the Solvay
process. The electrolysis of sodium chloride
produces sodium hypochlorite, NaOCl, a compound
of sodium, oxygen, and chlorine used in large
quantities in household chlorine bleach. Sodium
hypochlorite is also utilized as an industrial
bleach for paper pulp and textiles, for
chlorination of water, and in certain medicinal
preparations as an antiseptic and a fungicide. It
is an unstable compound known only in aqueous
solution.
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Sodium nitrate, or soda nitre, NaNO3, is commonly
called Chile saltpetre after its mineral deposits
in northern Chile, the principal source. Sodium
nitrate is used as a nitrogenous fertilizer and
as a component of dynamite.
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Sodium sulphate , Na2SO4, is a white crystalline
solid or powder employed in the manufacture of
kraft paper, paperboard, glass, and detergents
and as a raw material for the production of
various chemicals. It is obtained either from
deposits of the sodium sulfate minerals
mirabilite and thenardite or synthetically by the
treatment of sodium chloride with sulfuric acid.
The crystallized product is a hydrate,
Na2SO410H2O, commonly known as Glauber's salt.
Sodium thiosulphate (sodium hyposulfite),
Na2S2O3, is used by photographers to fix
developed negatives and prints it acts by
dissolving the unchanged silver salts
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Other familiar sodium compounds are the
carbonates, which contain the carbonate ion
(CO32-). Sodium bicarbonate, also called sodium
hydrogencarbonate, or bicarbonate of soda,
NaHCO3, is a source of carbon dioxide and so is
used as an ingredient in baking powders, in
effervescent salts and beverages, and as the main
constituent of dry-chemical fire extinguishers.
Its slight alkalinity makes it useful in treating
gastric or urinary hyperacidity and acidosis. It
is also employed in certain industrial processes,
as in tanning and the preparation of wool.
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Sodium carbonate , or soda ash, Na2CO3, is widely
distributed in nature, occurring as constituents
of mineral waters and as the solid minerals
natron, trona . Large quantities of this alkaline
salt are used in making glass, detergents, and
cleansers. Sodium carbonate is treated with
carbon dioxide to produce sodium bicarbonate. The
monohydrate form of sodium carbonate, Na2CO3H2O,
is employed extensively in photography as a
constituent in developers. Washing soda (sal
soda) consists of sodium carbonate decahydrate,
Na2CO3.10H2O it serves as a bleach for cotton
and linen
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