Question

A 10% aqueous solution of cane sugar (mol. wt. 342) is isotonic with 1.754% aqueous solution of urea. Find the molecular mass of urea. 

Answer 1

10% aqueous solution of cane sugar is isotonic with 1.754% aqueous solution of urea (M_B)

`(10 xx 1000)/(100 xx 342) = (1.754 xx 1000)/(100 xx M_B)`

`M_B = (1.754 xx 1000)/(100)`

= `(100 xx 342)/(10 xx 1000)`

= 1.754 × 34.2

= 59.99 ≈ 60

∴ The molecular mass of urea 60 g/mol.