Question

How many grams of urea should be dissolved in 500 gram water so that the depression in freezing point is 0.2 K? Kf for solvent is 3.2 K kg mole⁻¹.Solve the example.

Answer 1

Answer:

1.875 gm.

Explanation:

Quantity of water = 500gm (Given)

Freezing point = 0.2K (Given)

Kf solvent = 3.2 (Given)

Depression in Freezing point -

ΔT = i × kf × m

where m is the molarity of the solvent  , Kf is the cryoscopic  constant and t is the temperature.

Therefore,

0.2 = 3.2 × x/ 60 × 0.5

x = 30 × 2/32

x = 30/16

x = 1.875

Thus, the amount of uread required is 1.875 gm.