What is an Acid?
Acids are sour in taste, turn blue litmus red, and dissolve in water to release H+ ions.
Example: Sulphuric acid (H2SO4), Acetic Acid (CH3COOH), Nitric Acid (HNO3) etc.
Properties of Acids:
a) Acids have a sour taste.
b) Turns blue litmus red.
c) Acid solution conducts electricity.
d) Release H+ ions in an aqueous solution.
Types of Acids:
Acids are divided into two types on the basis of their occurrence i.e., Natural acids and Mineral acids.
(i) Natural Acids:
Acids that are obtained from natural sources are called Natural Acids or Organic Acids.
Examples: Methanoic acid (HCOOH), Acetic acid (CH3COOH), Oxalic acid (C2H2O4) etc.
|Organic Acids and their Sources|
|Ascorbic acid||Guava, amla|
|Citric acid||Lemon, orange and other citrus fruits|
|Lactic acid||Sour milk, curd|
|Methanoic acid||Ant sting, nettle sting|
(ii) Mineral Acids: Acids that are prepared from minerals are known as Mineral Acids Example; Inorganic acids, man-made acids or synthetic acid are also known as Mineral Acids.
Example: Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid (HNO3), Carbonic acid (H2CO3), Phosphoric acid (H3PO4) etc.
see also: Neutralization Reactions
Chemical Properties of Acid:
(i) Reaction of acids with metal: Acids give hydrogen gas along with respective salt when they react with a metal.
Metal + Acid → Salt + Hydrogen
Hydrogen gas and zinc chloride are formed when hydrochloric acid reacts with zinc metal.
(ii) Reaction of acids with metal carbonate: Acids give carbon dioxide gas and respective salts along with water when they react with metal carbonates.
Metal carbonate + Acid → Salt + Carbon dioxide + Water
Hydrochloric acid gives carbon dioxide gas, sodium chloride along with water when reacts with sodium carbonate.
iii) Reaction of acid with hydrogen carbonates (bicarbonates): Acids give carbon dioxide gas, respective salt and water when they react with metal hydrogen carbonate.
Acid + Metal hydrogen carbonate → Salt + Carbon dioxide + Water
Sulphuric acid gives sodium sulphate, Carbon dioxide gas and water when it reacts with sodium bicarbonate.