Some Basic Concepts of Chemistry - Result Question 41
####41. A compound $H _2 X$ with molar weight of $80 g$ is dissolved in a solvent having density of $0.4 g mL^{-1}$. Assuming no change in volume upon dissolution, the molality of a 3.2 molar solution is
(2014 Adv.)
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Solution:
- PLAN This problem can be solved by using concept of conversion of molarity into molality.
Molarity $=3.2 M$
Let volume of solution $=1000 mL=$ Volume of solvent
Mass of solvent $=1000 \times 0.4=400 g$
Since, molarity of solution is 3.2 molar
$$ \begin{aligned} n _{\text {solute }} & =3.2 mol \ \text { Molality }(m) & =\frac{3.2}{400 / 1000}=8 \end{aligned} $$
Hence, correct integer is (8).
