Salts: Definition, Types, Important Salts, Uses and Chemical Formulae
Introduction to Salts
In chemistry, salts are ionic compounds formed when an acid reacts with a base in a neutralization reaction. During this process, hydrogen ions (H⁺) of the acid are replaced by metal or ammonium ions (NH₄⁺), resulting in the formation of salt and water. Salts are widely used in daily life, industries, agriculture, medicine, and laboratories, making them a highly important topic for competitive examinations.
General Chemical Representation
Acid + Base → Salt + Water
Example:
HCl + NaOH → NaCl + H₂O
Classification of Salts
Salts are classified on the basis of the nature of acid and base from which they are formed.
Normal salts are formed by complete neutralization of an acid and a base.
Acidic salts contain replaceable hydrogen ions.
Basic salts contain hydroxyl ions.
Double salts are crystalline compounds containing two different salts.
Complex salts contain complex ions.
Important Salts, Chemical Formulae and Uses
Sodium Chloride (Common Salt)
Chemical Formula: NaCl
It is obtained mainly from sea water.
Uses include food preservation, seasoning, manufacture of washing soda, baking soda, hydrochloric acid, and chlorine.
It is essential for maintaining electrolyte balance in the human body.
Sodium Carbonate (Washing Soda)
Chemical Formula: Na₂CO₃·10H₂O
Prepared by the Solvay process.
Used in cleaning agents, glass manufacturing, soap making, and softening hard water.
It is an important laboratory reagent.
Sodium Bicarbonate (Baking Soda)
Chemical Formula: NaHCO₃
Used in baking powder to make cakes and bread fluffy.
Acts as an antacid to relieve acidity.
Used in fire extinguishers.
Calcium Carbonate
Chemical Formula: CaCO₃
Found naturally as limestone, marble, and chalk.
Used in cement manufacture, construction, and as an antacid.
Also used in toothpaste and paper industries.
Calcium Sulphate (Plaster of Paris)
Chemical Formula: CaSO₄·½H₂O
Used for making casts, statues, toys, and decorative items.
Used in hospitals for plaster casts.
Formed by heating gypsum at 100–120°C.
Copper Sulphate (Blue Vitriol)
Chemical Formula: CuSO₄·5H₂O
Used as a fungicide in agriculture.
Used in electroplating and dyeing.
Blue crystals lose water on heating and turn white.
Ammonium Chloride
Chemical Formula: NH₄Cl
Used in dry cells and fertilizers.
Used as an expectorant in medicines.
Sublimes on heating.
Potassium Nitrate
Chemical Formula: KNO₃
Used in fertilizers and gunpowder.
Important oxidizing agent.
Used in food preservation.
Ferrous Sulphate (Green Vitriol)
Chemical Formula: FeSO₄·7H₂O
Used to treat iron deficiency anemia.
Used in inks and dyes.
Turns brown on exposure due to oxidation.
Properties of Salts
Salts are generally crystalline solids.
Most salts are soluble in water.
They conduct electricity in molten or aqueous state.
Some salts are hygroscopic or efflorescent in nature.
Importance of Salts in Daily Life
Salts are essential for biological processes.
They play a key role in agriculture and soil fertility.
Industrial development heavily depends on salt-based chemicals.
Medicines and disinfectants contain various salts.
Important Exam Points
Neutral salts have pH equal to 7.
Acidic salts have pH less than 7.
Basic salts have pH greater than 7.
Washing soda is a hydrated salt.
Baking soda decomposes on heating.
Plaster of Paris sets by hydration.
Copper sulphate crystals are blue due to water of crystallization.
MCQ question🙋
1. A salt formed by complete neutralization of an acid and a base is called
A. Acidic salt
B. Basic salt
C. Normal salt
D. Double salt
Answer: C
2. The chemical formula of common salt is
A. Na₂CO₃
B. NaCl
C. NaHCO₃
D. KCl
Answer: B
3. Which salt is commonly used as an antacid?
A. Washing soda
B. Baking soda
C. Copper sulphate
D. Calcium chloride
Answer: B
4. Washing soda is chemically known as
A. Sodium bicarbonate
B. Sodium chloride
C. Sodium carbonate decahydrate
D. Calcium carbonate
Answer: C
5. Which salt is used in fire extinguishers?
A. NaCl
B. Na₂CO₃
C. NaHCO₃
D. KNO₃
Answer: C
6. The blue colour of copper sulphate crystals is due to
A. Copper metal
B. Sulphate ions
C. Water of crystallization
D. Impurities
Answer: C
7. Plaster of Paris is prepared by heating
A. Limestone
B. Calcium carbonate
C. Gypsum
D. Washing soda
Answer: C
8. The chemical formula of Plaster of Paris is
A. CaSO₄·2H₂O
B. CaSO₄
C. CaSO₄·½H₂O
D. CaCO₃
Answer: C
9. Which salt sublimes on heating?
A. Ammonium chloride
B. Sodium chloride
C. Calcium carbonate
D. Potassium nitrate
Answer: A
10. A salt having pH less than 7 is called
A. Neutral salt
B. Basic salt
C. Acidic salt
D. Double salt
Answer: C
11. Which salt is used in making glass and soap?
A. Baking soda
B. Washing soda
C. Common salt
D. Potassium nitrate
Answer: B
12. The salt used to cure iron deficiency anemia is
A. CuSO₄
B. FeSO₄
C. Na₂SO₄
D. ZnSO₄
Answer: B
13. Green vitriol is the common name of
A. Copper sulphate
B. Zinc sulphate
C. Ferrous sulphate
D. Ferric chloride
Answer: C
14. Which salt is an important oxidizing agent?
A. NaCl
B. KNO₃
C. CaCO₃
D. NH₄Cl
Answer: B
15. The salt obtained from sea water is
A. Washing soda
B. Baking soda
C. Common salt
D. Plaster of Paris
Answer: c