Question

The increase in boiling point of a solution containing 0.6g urea in 200 gram water is `0.50^(@)C`. Find the molal elevation constant
A. `10 K "gram" mol^(-1)`
B. `1.0 K kg mol^(-1)`
C. `10 K kg mol^(-1)`
D. `10 K kg` mol

Answer 1

Correct Answer - C
Molality, `m=(0.6)/(60)xx(1000)/(200)=0.05m`
`Delta T_(b)=0.5 K`
now `Delta T_(b)=K_(b)xxm`
or `K_(b)=(Delta T_(b))/(m)=(0.5)/(0.05)=10K kg mol^(-1)`