Question

Vant Hoff factor (i) for a dimension of acetic acid in chlorobenzene, assuming 30 % degree of association is:

• A. 0.85
• B. 0.95
• C. 0.9
• D. 0.7

Answer 1

Answer: (A)

0.85

For the dimerisation of acetic acid in benzene

$2C{H}_{3}COOH\to (C{H}_{3}COOH{)}_2$

2 moles of acetic acid associate to form 1 mole of dimer, so that

$i=1-(1-\frac{1}{2})\alpha =1-\frac{\alpha }{2}$

$i=1-\frac{30/100}{2}=0.85$