For sodium
sulfate
and
hydrochloric
acid to be formed from table
salt,
table
salt must react with sulfuric acid. This reaction
occurs
according
to the
following equation:
H2S04
+ 2
NaCl
=
Na2SO4 + 2
HCl.
The
atomic
weight
of Na
=
23, Cl
=
35.5,
H
=
1, hence
117 parts by
weight
of table salt
are
equivalent
to 73 parts
by
weight
of HCl.
If 39.5
kg
table salt
are
used and the
weight
of the HCl obtained
is denoted
by
x,
then
we
have the
following
proportion:
117:73
=
39.5:x
73
•
39.5
x
117
=
24.64
kg
gaseous hydrochloric acid.
However, since 30%
hydrochloric
acid
has been
used,
we
have
for the
weight of the diluted hydrochloric acid
y
the
following
equation:
30:100
=
24.64:y
y
=
82.1
kg
If
we
denote the unknown volume by
z,
and since the specific
gravity
of 30%
hydrochloric
acid is 1.15,
we
have
1:1.15
=
z
:82.1
82.
1
z
=
17115
-
71.4 l.
Hence.
71.4
e
30%
hydrochloric
acid
are
formed.
Substances formed:
1) Na2SO4 Glauber's salt.
Crystallizes
with 10 molecules of water of
crystallization, is water-soluble like all alkaline salts excepting
the
silicates,
has
a
bitter taste, and is used in medicine
as
a
laxative;
it is found in natural mineral waters. It is
an
intermediate
product
in the soda
process,
where
it
is reduced
to Na2S
(sodium
sulfide) by calcination with carbon.
2) HCl
hydrochloric
acid. This is
a
colorless,
pungent
gas
which
easily
dissolves in water.
Between
the
weight
and
percent
concentration of the solution there exists
a
relationship,
which has
been collected in tables,
i.e.,
the
specific
gravity increases with
increased HCl
content.
This is
a
rather strong
acid,
and it vigorously
attacks metals
and makes the litmus turn red. When
brought together
with
ammonia,
it the gaseous
hydrochloric acid forms
a
precipitate
NH4Cl.
Hydroiodic,
hydrobromic
and
hydrofluoric
acid
are
its
analogs.
24