At a certain place, pure water boils at 99.725°C. Calculate the boiling point of 0.69 m solution of urea in water at the same place. (Given kb of water = 0.513°C kg mol−1)
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 100.079°C
Urea is a non-electrolyte (i = 1), so the elevation of boiling point is
\( \Delta T_b = K_b\,m = 0.513 \times 0.69 = 0.354\ ^\circ\text{C} \)
The boiling point of the solution is the boiling point of pure water at that place plus this elevation:
\( T_b = 99.725 + 0.354 = 100.079\ ^\circ\text{C} \)