mal decomposition of sodium nitrate
and is used in the preparation of nitrous acid (reaction with cold dilute
hydrochloric acid). Sodium nitrite is
used in organic *diazotization and as
a corrosion inhibitor.
sodium nitroprusside test See
simon’s test.
sodium orthophosphate See
trisodium phosphate(v).
sodium peroxide A whitish solid
(yellow when hot), Na 2 O 2 , soluble in
ice-water and decomposed in warm
water or alcohol; r.d. 2.80; decomposes at 460°C. A crystalline octahydrate (hexagonal) is obtained by
crystallization from ice-water. The
compound is formed by the combustion of sodium metal in excess oxygen. At normal temperatures it
reacts with water to give sodium
hydroxide and hydrogen peroxide.
It is a powerful oxidizing agent reacting with iodine vapour to give the
iodate and periodate, with carbon at
300°C to give the carbonate, and
with nitrogen(II) oxide to give the
nitrate. It is used as a bleaching
agent in wool and yarn processing,
in the reÜning of oils and fats, and
in the production of wood pulp.
sodium sesquicarbonate A white
crystalline hydrated double salt,
Na 2 CO 3 .NaHCO 3 .2H 2 O, soluble in
water but less alkaline than sodium
carbonate; r.d. 2.12; decomposes on
heating. It may be prepared by crystallizing equimolar quantities of the
constituent materials; it also occurs
naturally as trona and in Searles
Lake brines. It is widely used as a
detergent and soap builder and,
because of its mild alkaline properties, as a water-softening agent and
bath-salt base. See also sodium carbonate.
sodium sulphate A white crystalline compound, Na 2 SO 4 , usually
known as the anhydrous compound
(orthorhombic; r.d. 2.67; m.p. 888°C)
or the decahydrate (monoclinic; r.d.
1.46; which loses water at 100°C).
The decahydrate is known as
Glauber’s salt. A metastable heptahydrate (Na 2 SO 4 .7H 2 O) also exists. All
forms are soluble in water, dissolving
to give a neutral solution. The compound occurs naturally as
mirabilite (Na 2 SO 4 .10H 2 O),
threnardite (Na 2 SO 4 ), and
glauberite (Na 2 SO 4 .CaSO 4 ).
Sodium sulphate may be produced
industrially by the reaction of magnesium sulphate with sodium chloride in solution followed by
crystallization, or by the reaction of
concentrated sulphuric acid with
solid sodium chloride. The latter
method was used in the *Leblanc
process for the production of alkali
and has given the name salt cake to
impure industrial sodium sulphate.
Sodium sulphate is used in the manufacture of glass and soft glazes and
in dyeing to promote an even Ünish.
It also Ünds medicinal application as
a purgative and in commercial aperient salts.
sodium sulphide A yellow-red
solid, Na 2 S, formed by the reduction
of sodium sulphate with carbon
(coke) at elevated temperatures. It is
a corrosive and readily oxidized material of variable composition and
usually contains polysulphides of the
type Na 2 S 2 , Na 2 S 3 , and Na 2 S 4 , which
cause the variety of colours. It is
known in an anhydrous form (r.d.
1.85; m.p. 1180°C) and as a nonahydrate, Na 2 S.9H 2 O (r.d. 1.43; decomposes at 920°C). Other hydrates of
sodium sulphide have been reported.
The compound is deliquescent, soluble in water with extensive hydrolysis, and slightly soluble in alcohol. It
is used in wood pulping, dyestuffs
manufacture, and metallurgy on acsodium nitroprusside test
492
s
www.AzShimi.ir www.AzShimi.com
and is used in the preparation of nitrous acid (reaction with cold dilute
hydrochloric acid). Sodium nitrite is
used in organic *diazotization and as
a corrosion inhibitor.
sodium nitroprusside test See
simon’s test.
sodium orthophosphate See
trisodium phosphate(v).
sodium peroxide A whitish solid
(yellow when hot), Na 2 O 2 , soluble in
ice-water and decomposed in warm
water or alcohol; r.d. 2.80; decomposes at 460°C. A crystalline octahydrate (hexagonal) is obtained by
crystallization from ice-water. The
compound is formed by the combustion of sodium metal in excess oxygen. At normal temperatures it
reacts with water to give sodium
hydroxide and hydrogen peroxide.
It is a powerful oxidizing agent reacting with iodine vapour to give the
iodate and periodate, with carbon at
300°C to give the carbonate, and
with nitrogen(II) oxide to give the
nitrate. It is used as a bleaching
agent in wool and yarn processing,
in the reÜning of oils and fats, and
in the production of wood pulp.
sodium sesquicarbonate A white
crystalline hydrated double salt,
Na 2 CO 3 .NaHCO 3 .2H 2 O, soluble in
water but less alkaline than sodium
carbonate; r.d. 2.12; decomposes on
heating. It may be prepared by crystallizing equimolar quantities of the
constituent materials; it also occurs
naturally as trona and in Searles
Lake brines. It is widely used as a
detergent and soap builder and,
because of its mild alkaline properties, as a water-softening agent and
bath-salt base. See also sodium carbonate.
sodium sulphate A white crystalline compound, Na 2 SO 4 , usually
known as the anhydrous compound
(orthorhombic; r.d. 2.67; m.p. 888°C)
or the decahydrate (monoclinic; r.d.
1.46; which loses water at 100°C).
The decahydrate is known as
Glauber’s salt. A metastable heptahydrate (Na 2 SO 4 .7H 2 O) also exists. All
forms are soluble in water, dissolving
to give a neutral solution. The compound occurs naturally as
mirabilite (Na 2 SO 4 .10H 2 O),
threnardite (Na 2 SO 4 ), and
glauberite (Na 2 SO 4 .CaSO 4 ).
Sodium sulphate may be produced
industrially by the reaction of magnesium sulphate with sodium chloride in solution followed by
crystallization, or by the reaction of
concentrated sulphuric acid with
solid sodium chloride. The latter
method was used in the *Leblanc
process for the production of alkali
and has given the name salt cake to
impure industrial sodium sulphate.
Sodium sulphate is used in the manufacture of glass and soft glazes and
in dyeing to promote an even Ünish.
It also Ünds medicinal application as
a purgative and in commercial aperient salts.
sodium sulphide A yellow-red
solid, Na 2 S, formed by the reduction
of sodium sulphate with carbon
(coke) at elevated temperatures. It is
a corrosive and readily oxidized material of variable composition and
usually contains polysulphides of the
type Na 2 S 2 , Na 2 S 3 , and Na 2 S 4 , which
cause the variety of colours. It is
known in an anhydrous form (r.d.
1.85; m.p. 1180°C) and as a nonahydrate, Na 2 S.9H 2 O (r.d. 1.43; decomposes at 920°C). Other hydrates of
sodium sulphide have been reported.
The compound is deliquescent, soluble in water with extensive hydrolysis, and slightly soluble in alcohol. It
is used in wood pulping, dyestuffs
manufacture, and metallurgy on acsodium nitroprusside test
492
s
www.AzShimi.ir www.AzShimi.com