The value of any colligative property of any electrolyte is determined experimentally, it is found to be higher than the theoretically calculated vallue using the usual expressions. This is because the electrolytes undergo dissociation in the solution. Similarly, in case of some substances association takes place, e.g., acetic acid in benzene and the experimental value of colligative value. The experimentally observed molar masses come out to be different than the theoretical values. These are called abnormal molar masses. In such cases, a correction factor, i, called van't Hoff factor is introduced which is a ratio of observed value of colligative property to calculated value when the solution behaves ideally. Knowing i, the degree of dissociation or association of the solute can be calculated.
The van't Hoff factor for `0.1 M Ba(NO_(3))_(2)` solution is 2.74. The degree of dissociation is

Options

A. `91.3%`
B. `87%`
C. `100%`
D. `74%`

Answer

B

Explanation

`{:(,Ba(NO_(3))_(2),hArr,Ba^(2+),+,2NO_(3)^(-)),("Initial","1 mole",,,,),("After disso.",1-alpha,,alpha,,2alpha):}`
Total `=1+2alpha`
`therefore i=1+2alpha`
or `alpha=(i-1)/(2)=(2.74-1)/(2)=0.87=87%`