A solution of `0.450` g of urea (mol wt. `60`)in `22.5g`of water showed `0.170^(@)C` of elecation in boiling point. Calculate the molal elevation constant of water

Options

A. `0.17^@C`
B. `0.45^@C`
C. `0.51^@C`
D. `0.30^@C`

Answer

C

Explanation

Wt. of solute, w = 0.450 g
Wt. of solvent , W = 22.5 g
Mol. wt of solute, m = 60
Molal elevation constant `K_b` = ?
Boiling point elevation , `DeltaT_b = 0.170^@C`
Substituting these values in the equation
`K_b=(mxxWxxDeltaT_b)/(1000xxw)`
`=(60xx22.5xx0.170)/(1000xx0.450)=0.51^@C`