2. CHEMICALS FROM SALTS
What are salts?
- When a metal combines with an acid, it
forms a compound called a salt.
Reaction:
Acid+ Metal Salt+ Hydrogen gas
For ex.
NaOH(aq)+HCl(aq) NaCl(aq)+H2O(l)
3.
4. COMMON SALT
Salt formed by the combination of
hydrochloride acid & sodium hydroxide
solution is called sodium chloride. This
is the salt we use in food. It is a neutral
salt or common salt.
Seawater contains many salts dissolved in
it. Sodium chloride is separated from
these salts.
5. Deposits of solid salt are also found in
several parts of the world. These large
crystals are often brown due to the
impurities. This is called rock salt.
Beds of rock salt were formed when seas
of bygone ages dried up. Rock salt is
mined like coal.
6.
7. Raw material for
Chemicals
The common salt is an important raw
material for various materials of daily
use. Some of those are:
8. Sodium Hydroxide
When electricity is passed through a
saturated aqueous solution of sodium
chloride (brine), it decomposes to form
sodium hydroxide.
This process is called chlor- alkali process
because of the products formed –
chlor for chlorine & alkali for sodium
hydroxide.
2NaCl+2H2O 2NaOH+Cl2+H2
9. Bleaching Powder
The chlorine produced during the
electrolysis of aqueous sodium chloride
is used for the manufacture of bleaching
powder.
Bleaching powder is produced by the
action of chlorine on dry slaked lime.
Ca(OH)2 + Cl2 CaOCl2 + H2O
10. Bleaching powder is used –
For bleaching cotton & linen in the textile
industry, for bleaching wood pulp in
paper factories & for bleaching washed
clothes in laundry.
As an oxidising agent in many chemical
industries.
For disinfecting drinking water to make it
free of germs.
11. Baking Soda
The soda commonly used in the kitchen
for making food crispy is baking soda.
Sometimes it is added for faster cooking.
The chemical name of the compound is
sodium hydrogencarbonate. It is
produced using sodium chloride as one
of the raw materials.
NaCl+H2O+CO2+NH3 NH4Cl+NaHCO3
12. Uses of sodium hydrogencarbonate
For making baking powder, which is a
mixture of baking soda &a mild edible
acid such as tartaric acid.
Sodium hydrogencarbonate is also an
ingredient in antacids. Being alkaline, it
neutralises excess acid in the stomach
& provides relief.
It is also used in soda- acid fire
extinguishers.
13.
14. Washing Soda
Another chemical that can be obtained
from sodium chloride is washing soda.
Sodium carbonate can be obtained by
heating baking soda; recrystallisation of
sodium carbonate gives washing soda.
It is also a basic salt.
Na2CO3 + 10H2O Na2CO3.10H2O
15. Uses of washing soda
Sodium carbonate is used in glass,
soap & paper industries.
It is used in the manufacture of
sodium compounds such as borax.
Sodium carbonate can be used as a
cleaning agent for domestic purposes.
It is used for removing permanent
hardness of water.
