A 2% sucrose solution is isotonic with 1.5% solution of an unknown substance. What is the molecular mass of the unknown substance.
Answer & explanation
Correct answer: option 1
For isotonic solution,
π1 = π2
or C1 = C2
or \(\frac{W_1/M_1}{V_1}\) = \(\frac{W_2/M_2}{V_2}\)
for V1 = V2 = 100,
\(\frac{2}{342 × 100}\) = \(\frac{1.5}{M_2 × 100}\)
M2 = \(\frac{342 × 1.5}{2}\) = 171 x 1.5 = 256.5 g