Question

Q.An aqueous solution of urea is isotonic with 12 g/l glucose solutions at 300k. The concentration of urea is.​

Answer 1

Answer: 0.06 M

Explanation:

Isotonic solutions are those solutions which have the same osmotic pressure.  If osmotic pressures are equal at the same temperature, concentrations must also be equal.

$\pi =CRT$ for non electrolytes such as glucose

$\pi$ = osmotic pressure

C= concentration

R= solution constant

T= temperature

Thus:- $C_{urea}=C_{glucose}$ where concentration is in molarity.

For glucose: 12 g of glucose is dissolved in 1000 ml of solution.

$Molarity=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{volume of solution in ml}}$

$C_{glucose}=\frac{12\times 1000}{180\times 100}=0.06M$