Question

$A$ solution is made by dissolving $20\, g$ of a substance in $500\, mL$ of water. Its osmotic pressure was found to be $600\, mm$ of $Hg$ at $15\,{}^°C$. Find the molecular weight of the substance.

• A. $1198$
• B. $500$
• C. $1200$
• D. $1000$

Answer 1

Answer: (A)

$M = \frac{W_{B}RT}{\pi V}$
$= \frac{20 \times0.0812 \times 288 \times 1000}{\left(600/760\right)\times 500} = 1198$