CHAPTER - 2
ACIDS, BASES AND SALTS

ACIDS: Acid is a substance which furnishes H+ ions or H3O+ ions when dissolved in water. Acids have one or more replaceable hydrogen atoms. The word acid is derived from the Latin name ‘Acidus’ which means Sour Taste. Substances with ‘sour taste’ are acids. Lemon juice, vinegar and grape juice have sour taste, so they are acidic.
Substances which turn blue litmus solution red are called acids.

CLASSIFICATION OF ACIDS:
Ø  Based on Source: Acids are of two types Mineral acids (Inorganic acid), Organic acid.
v Acids which are obtained from minerals and rocks are called Mineral acids. For e.g., H2SO4 (Sulphuric acid), HNO3 (Nitric acid) and HCl (Hydrochloric  acid).
v Acids which are extracted from plants and animals are called Organic acids. For e.g. Citric acid (C6H8O7), Ascorbic acid (C6H8O6), Tartaric acid (C4H6O6), Lactic acid (C3H6O3), Acetic acid (C2H4O2).

Ø  Based on ionisation: Acids are classified into two types based on ionisation.
v Strong acids: Completely dissociate into its ions in aqueous solutions. Example: Nitric acid (HNO3), Sulphuric acid (H2SO4), Hydrochloric acid (HCl).
v Weak acids: Which do not completely dissociate into its ions in aqueous solutions. For example: Carbonic acid (H2CO3), acetic acid (CH3COOH).

Ø  Based on concentration: Depending on the percentage or amount of acid dissolved in water acids are classified into dilute acid and concentrated acid.
v Dilute acids: Have a low concentration of acids in aqueous solutions.
v Concentrated acids: Have a high concentration of acids in aqueous solutions.

Ø  Based on their number of Hydrogen ion acids are:
v Monoprotic acid: Such type of acid produces one mole of H+ ions per mole of acid, e.g., HCl, HNO3.
v Diprotic acid: They can produce two moles of H+ ions per mole of acid, e.g., H2SO4.
v Triprotic acid: They produce three moles of H+ ions per mole of acid, e.g., H3PO4.
                    v Polyprotic: They can produce more than three H+ ions per mole of acid.