Page 44 - Science Class 07

v To manufacture chemicals such as glue. v To prepare aqua regia.

v To purify salts. v To extract some metals from their ores.
v To remove scales, i.e., the deposits formed v To purify precious metals such as silver and

inside boilers in various industries. The gold.
process is known as descaling. BASIC SUBSTANCES
v To make auqa regia. Baking soda tastes bi er. Prepare a solu on of

Aqua regia consists of 3 parts of hydro- baking soda in water and rub it between your
chloric acid and 1 part of nitric acid. It is fingers. Does it feel soapy? Substances such as
used to dissolve noble metals such as gold baking soda that are bi er in taste and feel
and pla num. soapy to touch are called bases.

Sulphuric Acid A base can neutralize an acid’s acidity. When
Sulphuric acid is one of the most widely used people suffer from ‘acidity’ in the stomach they
chemicals in industry. take an antacid. Antacids are bases. They
neutralize the acid in the stomach. Several
Its main uses are as follows:
antacids contain the base magnesium hyd-
v To manufacture fer lizers such as ammo-
roxide or aluminum hydroxide. Magnesium
nium sulphate and superphosphate.
hydroxide and aluminum hydroxide are mild
v In automobile ba eries. bases. Calcium hydroxide is a strong base.
v To manufacture detergents. Sodium hydroxide and potassium hydroxide
v To manufacture drugs, plas cs, paints, etc. from which soap is made are also strong bases.

v To manufacture several chemicals such as
Strong Bases Formula
copper sulphate, epsom salts, etc.
v In tex le, paper and leather industries. Sodium hydroxide NaOH

Potassium hydroxide KOH

Weak bases Formula

Ammonium hydroxide NH OH
4
Calcium hydroxide Ca(OH)
2
Magnesium hydroxide Mg(OH)
2

Prepara on of Bases
Bases are formed by combina on of metal
Sulphuric Acid Plant
directly with oxygen. Metals when heated with
Nitric acid
oxygen, metal oxides formed, e.g.,
Its main uses are as follows:
4Na + O 2Na O
v To manufacture fer lizers such as ammo- 2 2
(Sodium) + (Oxygen) (Sodium oxide)
nium nitrate.
2Mg + O 2MgO
v To manufacture explosives such as TNT 2
(Magnesium) (Oxygen) (Magnesium oxide)
(trinitrotoluene) and nitroglycerine.

44 Science-7