Question

Find the mass of sodium carbonate in grams to form 100 ml 0.1 M solution in water?
( Molar mass of \(\text{Na}_2\text{CO}_3\) = 106 g/mol)

• A. \(1.06\) g
• B. \(3.18\) g
• C. \(2.12\) g
• D. \(4.16\) g

Hint:

Moles = molarity x volume in litres, then multiply by the molar mass.

Answer 1

The Correct Option is A

Step 1: Convert volume
100 mL is 0.1 L.

Step 2: Moles from molarity
Molarity tells the moles in each litre, so 0.1 M in 0.1 L holds $0.1 \times 0.1 = 0.01$ mol of $\text{Na}_2\text{CO}_3$.

Step 3: Convert to mass
Each mole weighs 106 g, so $0.01 \times 106 = 1.06$ g. Options (B) and (C) would give 0.3 M and 0.2 M, so they do not match 0.1 M.

Final Answer:
The mass required is 1.06 g, option (A). \[ \boxed{1.06 \text{ g}} \]