Question

An aqueous solution of urea containing 18g urea in 15 $c{m}^3$ of the solution has a density equal to 1.052 $g/c{m}^3$. If the molecular weight of urea is 60, then the molality of the solution is:

• A. 0.2
• B. 0.192
• C. 0.1
• D. 1.2

Answer 1

Answer: (B)

0.192

Little correction volume $=150cuB$

density of solution, $d=1.052g/c{m}^3$

volume of solution $=1500c{m}^3$

Mass of rotation $=density\times volume$

$=1.052\times 15g\times {10}^2$

$=1578gm$

Amount of urea $=18g$

amount of water $=1578-18=1560g$

Number of mole of urea $=\frac{18g}{60}=0.3$

molality $=\frac{0.3}{1560\times {10}^{-3}}=0.192m$