Which from the following statements is correct for aqueous solution of $6 \mathrm{gL}^{-1}$ urea and $17…
Which from the following statements is correct for aqueous solution of $6 \mathrm{gL}^{-1}$ urea and $17 \cdot 12 \mathrm{~g} \mathrm{~L}^{-1}$ of sucrose?
[Molar mass of urea $=60 \mathrm{~g} \mathrm{~mol}^{-1}$
Molar mass of sucrose $=342 \mathrm{~g} \mathrm{~mol}^{-1}$ ]
Osmotic pressure exhibited by urea solution is lower than that of sucrose solution.
Urea solution is hypertonic to sucrose solution,
These solutions are isotonic.
On doubling the concentration of sucrose solution it becomes hypertonic to urea solution.
Solution
$\mathrm{M}_{\text {urea }}=\frac{\text { mass of urea in solution }}{\text { molar mass of urea } \times \text { volume of solution (in } L \text { ) }}$
$=\frac{\frac{6 \mathrm{~g}}{60 \mathrm{~g} \mathrm{~mol}^{-1}}}{1 \text { Litre }}=0.1 \mathrm{~mol} \mathrm{~L}^{-1}$
$\mathrm{M}_{\text {sucrose }}=\frac{\text { mass of sucrose in solution }}{\text { molar mass of sucrose } \times \text { volume of solution (in } L \text { ) }}$
$=\frac{\frac{17.12 \mathrm{~g}}{342 \mathrm{~g} \mathrm{~mol}^{-1}}}{1 \mathrm{Litre}^2}=0.05 \mathrm{~mol} \mathrm{~L}^{-1}$
Urea has higher solute concentration $(0.1 \mathrm{M})$ than sucrose ( 0.05 M ).
Thus, urea solution is hypertonic to sucrose.