Question

Question Number: 83 QUELLIUL. IU.
Orientation : Vertical
8 grams of substance of molecular weight 40 is dissolved in 250 g of water. Then the
molality of the solution is​

Answer 1

Explanation:

12g of a non-volatile solute dissolved in 108g of water produces the relative lowering of vapour pressure of 0.1. The molecular mass of the solute is 20.

P

0

ΔP

=0.1

P

0

ΔP

=

W

1

M

2

W

2

M

1

0.1=

108 g ×M

2

12 g × 18 g/mol

M

2

= 20 g/mol

Note: W

1

and W

2

are weights of water and solute respectively.

M

1

and M

2

are molecular weights of water and solute respectively.