This is a reaction in which a salt reacts with water to form a solution which is either acidic or basic in nature.

a) Salt of weak alkali and strong acid

NH₄Cl + H₂O NH₄OH + HCl

(Slightly acidic)

b) Salt of strong alkali and weak acid

K₂CO₃ + H₂O 2KOH + H₂CO3

(Slightly basic)

c) Strong alkali and strong acid

NaCl + H₂O Not hydrolyse

(neutral)

The property of hydrated crystals to loose water of crystallization is called efflorescence.

e.g. Washing soda ( Na₂CO₃ . 10 H₂O )

Glauber’s salt ( Na₂SO₄ . 10 H₂O )

Epson salt ( MgSO₄ . 7 H₂O )

Certain salts when exposed to atmosphere, absorb moisture, becomes moist and ultimately dissolve in absorbed water forming a saturated solution.

e.g. CaCl₂.6H₂O, FeCl₃, NaOH

When a salt exposed to atmosphere, absorbs moisture without dissolving in it, this property is called Hygroscopy.

e.g. Anhydrous CaCl₂, Silica gel, CaO

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[next chapter]

Index

12.1 - Lowry and Bronsted Concept
12.2 - Conjugate Acid Base Pairs
12.3 - Amphoteric Substance
12.4 - Lewis Acids and Bases
12.5 - Strong and Weak Acids and Bases
12.6 - Dissociation
12.7 - Ostwald's Dilution Law
12.8 - Hydrogen Ion Concentration : pH
12.9 - Polyprotic Acids
12.10 - Salts
12.11 - Methods of Preparation of Salts
12.12 - Properties of Salts

Chapter 13