Question 51

The density of 3M solution of NaCl is $$1.0 \text{ g mL}^{-1}$$. Molality of the solution is ______ $$\times 10^{-2}$$ m (Nearest integer).
Given: Molar mass of Na and Cl is 23 and 35.5 $$\text{g mol}^{-1}$$ respectively.

Correct Answer: 364

3M NaCl, density 1 g/mL. 1L solution: mass=1000g. Moles NaCl=3. Mass NaCl=3×58.5=175.5g. Mass water=1000-175.5=824.5g=0.8245kg.

Molality=3/0.8245=3.638 m = 364×10⁻² m.

The answer is $$\boxed{364}$$.

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The density of 3M solution of NaCl is $$1.0 \text{ g mL}^{-1}$$. Molality of the solution is ______ $$\times 10^{-2}$$ m (Nearest integer).Given: Molar mass of Na and Cl is 23 and 35.5 $$\text{g mol}^{-1}$$ respectively.