Chemistry - Liquid Solution Question with Solution | TestHub

For isotonic solutions, the osmotic pressures are equal, which implies their molar concentrations are equal at the same temperature.

$C_A=C_B$

Given $C_A=0.1$ M

For solution B, mass of solute $W_B=1.5$ g and volume of solution $V=100$ cm${}^3=0.1$ L.

$C_B=\frac{W_B}{M_B\times V}=\frac{1.5}{M_B\times 0.1}=\frac{15}{M_B}$

Equating the concentrations:

$0.1=\frac{15}{M_B}$

$M_B=\frac{15}{0.1}=150$ g mol${}^{-1}$

Answer: $150gmo{l}^{-1}$