Question

Salts play a very important role in our daily life. Sodium chloride which is known as common salt is used almost in every kitchen. Baking soda is also a salt used in faster cooking as well as in baking industry. The family of salts is classified on the basis of cations and anions present in them.
(a) Identify the acid and base from which Sodium chloride is formed.
(b) Find the cation and the anion present in Calcium sulphate.
(c) “Sodium chloride and washing soda both belong to the same family of salts.” Justify this statement.
OR
(c) Define the term pH scale. Name the salt obtained by the reaction of Potassium hydroxide and Sulphuric acid and give the pH value of its aqueous solution.

Answer 1

Salts in Daily Life
Salts are chemical compounds formed by the neutralization of an acid and a base. They play important roles in food, industry, and health. Let's answer each part step by step.

(a) Identify the acid and base from which Sodium chloride is formed.
Sodium chloride (NaCl) is formed by the neutralization reaction between:
- Hydrochloric acid (HCl) → acid
- Sodium hydroxide (NaOH) → base

Reaction: HCl + NaOH → NaCl + H₂O

(b) Find the cation and the anion present in Calcium sulphate.
- Chemical formula of Calcium sulphate is CaSO₄
- Cation: Ca²⁺ (Calcium ion)
- Anion: SO₄²⁻ (Sulphate ion)

(c) “Sodium chloride and washing soda both belong to the same family of salts.” Justify this statement.
- Sodium chloride (NaCl) and washing soda (Na₂CO₃) both contain sodium (Na⁺) as the cation.
- Salts having the same cation or anion are considered to belong to the same family.
- Hence, both salts belong to the sodium salt family.

OR

(c) Define the term pH scale. Name the salt obtained by the reaction of Potassium hydroxide and Sulphuric acid and give the pH value of its aqueous solution.
- pH scale: It is a scale that measures the hydrogen ion concentration (H⁺) in a solution. It ranges from 0 to 14.
- pH < 7 → Acidic solution
- pH = 7 → Neutral solution
- pH > 7 → Basic solution

- Reaction of Potassium hydroxide (KOH) and Sulphuric acid (H₂SO₄) gives:
2KOH + H₂SO₄ → K₂SO₄ + 2H₂O
So, the salt formed is Potassium sulphate (K₂SO₄).
- Potassium sulphate is a neutral salt (formed from strong acid and strong base), so its pH is approximately 7.

Final Answers:
(a) Acid: HCl, Base: NaOH
(b) Cation: Ca²⁺, Anion: SO₄²⁻
(c) Both NaCl and Na₂CO₃ have Na⁺ ion, so they belong to the same family
OR
(c) pH scale measures hydrogen ion concentration; Salt: Potassium sulphate (K₂SO₄); pH ≈ 7