Aqueous solution (by mass) of urea has boiling point
. The boiling point of
glucose in watar :- ‘?oint noint of water is
) (1)
(2)
(3)
(4)
The Correct Answer and Explanation is:
The correct answer is 373.47 K.
Explanation:
The boiling point elevation of a solution depends on the number of dissolved particles, which is determined by the van’t Hoff factor (ii) and the molal concentration of the solute. The equation used to calculate the boiling point elevation is:
ΔTb=iKbm\Delta T_b = i K_b m
where:
- ΔTb\Delta T_b is the boiling point elevation,
- ii is the van’t Hoff factor (the number of particles into which the solute dissociates),
- KbK_b is the ebullioscopic constant of the solvent (for water, Kb=0.512K_b = 0.512 K·kg/mol),
- mm is the molality of the solution.
Urea is a non-electrolyte and does not dissociate in solution, so its van’t Hoff factor is 1. The boiling point of the 10% aqueous urea solution is given as 374.11 K, meaning it experienced boiling point elevation.
Similarly, glucose is also a non-electrolyte and does not dissociate in water. A 10% glucose solution has a similar number of dissolved molecules, but since glucose has a higher molar mass (180 g/mol) than urea (60 g/mol), its molality is lower for the same mass percent.
Since boiling point elevation is directly proportional to molality, a 10% glucose solution will experience a slightly lower increase in boiling point compared to urea. This results in a boiling point of 373.47 K, which is the correct answer.
The difference in boiling points arises due to the fact that urea has a lower molar mass, resulting in more dissolved moles for the same mass percent and greater colligative effects. This explains why urea’s solution has a higher boiling point elevation than glucose’s solution, even though both are non-electrolytes.
