Question

Which of the following statements are correct for van't Hoff's factor 'i' for a solution of weak electrolytes $A_x{B}_y$?

• A. $i=1-\alpha +X\alpha +Y\alpha$
• B. i > 1 at normal dilution
• C. i increases more rapidly with dilution and attains a limiting value of (x+y) at infinite dilution
• D. the increases in 'i' with dilution is due to increase in molality of solution with dilution

Answer 1

Answer: (A), (B), (C)

The correct options are
A $i=1-\alpha +X\alpha +Y\alpha$
B i > 1 at normal dilution
C i increases more rapidly with dilution and attains a limiting value of (x+y) at infinite dilution

Option (A),(B),(C) are correct.
Van't hoff factor for week electrolytes is greater than 1 but less than the total number of ions available for dissociation.The increases in 'i' with dilution is due to decrease in molality of solution with dilution.