0.1 molal aqueous solution of glucose boils at $100.16^{\circ} \mathrm{C}$. What is boiling point of 0.5…

0.1 molal aqueous solution of glucose boils at $100.16^{\circ} \mathrm{C}$. What is boiling point of 0.5 molal aqueous solution of glucose?
  1. $100.80^{\circ} \mathrm{C}$
  2. $100.16^{\circ} \mathrm{C}$
  3. $100.10^{\circ} \mathrm{C}$
  4. $20.8^{\circ} \mathrm{C}$

Solution

Given: - 0.1 molal solution boils at $100.16^{\circ} \mathrm{C}$. - Boiling point elevation formula: $\Delta T_b=i K_b \cdot m$ where $m$ is molality. Step 1: Elevation for 0.1 molal solution: $\Delta T_b=100.16-100=0.16^{\circ} C$
Using $\Delta T_b \propto m$, for 0.5 molal solution: $\Delta T_b^{\prime}=0.16 \cdot \frac{0.5}{0.1}=0.8^{\circ} \mathrm{C}$
Step 2: New Boiling Point: $T_b^{\prime}=100+0.8=100.80^{\circ} \mathrm{C}$
Answer: $100.80^{\circ} C$, Option 1.

Asked in: MHT CET 2024 (10 May Shift 1)

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