Question

The chemical formula of washing soda is :

• A. \(Na_2CO_3 \cdot 10H_2O\)
• B. \(NaHCO_3\)
• C. \(CH_3COONa\)
• D. \(Na_2CO_3\)

Hint:

Distinguish between the two forms of sodium carbonate:
- \(Na_2CO_3\) = Soda Ash (Anhydrous, no water).
- \(Na_2CO_3 \cdot 10H_2O\) = Washing Soda (Decahydrate, has 10 water molecules).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the correct chemical formula representing washing soda, which is a widely used cleaning agent.

Step 2: Key Formula or Approach:
Washing soda is chemically named sodium carbonate decahydrate, representing a crystallized sodium carbonate salt with ten molecules of water of crystallization.

Step 3: Detailed Explanation:

• The chemical name for washing soda is sodium carbonate decahydrate.

• Its chemical formula is written as:
\[ Na_2CO_3 \cdot 10H_2O \] - It is prepared industrially via the Solvay process.

• Let us analyze the other options:
- (B) \(NaHCO_3\): This is sodium bicarbonate, commonly known as baking soda.
- (C) \(CH_3COONa\): This is sodium acetate, which is a sodium salt of acetic acid.
- (D) \(Na_2CO_3\): This is anhydrous sodium carbonate, commonly known as soda ash. It does not contain any water of crystallization.

• When soda ash is recrystallized from an aqueous solution, it binds with ten molecules of water to form washing soda:
\[ Na_2CO_3 + 10H_2O \to Na_2CO_3 \cdot 10H_2O \] - This hydrated salt is an alkaline salt that helps in removing dirt and grease from clothes by emulsifying oils.


Step 4: Final Answer:
The chemical formula of washing soda is \(Na_2CO_3 \cdot 10H_2O\).