The osmotic pressure of CaCl2 and urea solutions of the same concentration at the same temperature are respectively 0.605 atm and 0.245 atm, calculate van’t Hoff factor for CaCl2. - Chemistry

Exercise | Q 3.4 | Page 46

Answer the following.

The osmotic pressure of CaCl2 and urea solutions of the same concentration at the same temperature are respectively 0.605 atm and 0.245 atm, calculate van’t Hoff factor for CaCl2.

Solution:

Given: Osmotic pressure of CaCl2 solution = 0.605 atm

Osmotic pressure of urea solution = 0.245 atm

To find: The value of van’t Hoff factor

Formulae: π = MRT, π = iMRT

Calculation: For urea solution

π = MRT

0.245 atm = MRT       ....(i)

For CaCl₂ solution

π = iMRT

0.602 atm = iMRT       ....(ii)

From equations (i) and (ii),

${\displaystyle \frac{0.605}{0.245}=\frac{\text{iMRT}}{\text{MRT}}}$

∴ i = 2.47

The value of van’t Hoff factor is 2.47.