Visha took two aqueous solutions, one containing 7.5 g of urea (Molar mass = 60 g/mol) and the other containing 42.75 g of substance Z in 100 g of water, respectively. It was observed that both the solutions froze at the same temperature. Calculate the molar mass of Z.

Answer

`342 g mol^(-1)`

Explanation

For urea , ` " " M_(B) = (k_(f) xx 7.5 xx 1000)/(Delta T_(f) xx 100) = 60`
For X, `M_(B) = (k_(f) xx 42.75 xx 1000)/(Delta T_(f) xx 100)`
Dividing `(60)/(M_(B)) = (7.5)/(42.75) or M_(B) = 342`