A solution containing 36 g of glucose (molar mass = 180 g mol−1) per litre has an osmotic pressure of 4.98 bar at 27°C. If the osmotic pressure of another glucose solution is 1.52 bar at the same temperature, what is its concentration?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 0.061 M
The osmotic pressure of a dilute solution is proportional to its molar concentration at a given temperature:
\( \displaystyle \Pi=CRT \)
Both solutions are at 27°C, so R and T cancel in the ratio:
\( \displaystyle \frac{\Pi_2}{\Pi_1}=\frac{C_2}{C_1} \)
Concentration of the first solution:
\( \displaystyle C_1=\frac{36/180\,\mathrm{mol}}{1\,\mathrm{L}}=0.2\,\mathrm{M} \)
Concentration of the second solution:
\( \displaystyle C_2=0.2\times\frac{1.52}{4.98} \)
\( \displaystyle C_2=0.061\,\mathrm{M} \)