Question

Calculate the boiling point of urea solution when 8.0g of urea is dissolved in 250g of water. Boiling point of pure water is 373K.

(k_b of water = 0.52 K kg mol^-1, molecular mass of urea = 60 g mol^-1)

Answer 1

To calculate the boiling point of a urea solution, the boiling point elevation formula:

ΔT_b = i × k_b × m

where,

ΔT_b = 0.277 K (boiling point elevation)

i = Van't Hoff factor

K_b = 0.52 K·kg/mol

m = molality of the solution.

As we know, 

`"T"_"solution" = "T"_"pure solvent" + Δ"T"_"b"`

`"T"_"solution"` = 373 K + 0.277 K

`"T"_"solution"` = 373.277 K

∴ boiling point of the urea solution is 373.277 K