The boiling point of pure water is . What will be the exact boiling point of an aqueous solution con — Solutions and Colligative Properties Chemistry Question
Question
The boiling point of pure water is $100^\circ\text{C}$. What will be the exact boiling point of an aqueous solution containing $0.6\text{ g}$ of urea (molar mass $= 60\text{ g mol}^{-1}$) in $100\text{ g}$ of water? ($K_b = 0.52\text{ K kg mol}^{-1}$).
Answer: C
💡 Solution & Explanation
Urea is a non-electrolyte ($i=1$). Molality $m = \frac{0.6/60}{100/1000} = \frac{0.01}{0.1} = 0.1\text{ m}$. Elevation in boiling point $\Delta T_b = 1 \times 0.52 \times 0.1 = 0.052^\circ\text{C}$. Therefore, the new boiling point $= 100 + 0.052 = 100.052^\circ\text{C}$.
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