Sample 1Medium
A weak monobasic acid HA dissociates in water as HA ⇌ H^+ + A^-. If the van't Hoff factor of its solution is 1.2, what is the degree of dissociation?
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The answer is B.
For dissociation into two ions, i = 1 + α. So α = i − 1 = 1.2 − 1 = 0.2, that is 20%.
- A.
This divides (i − 1) by 2, which would apply only if the acid gave three ions.
- C.
40% would give i = 1.4.
- D.
80% is the fraction left undissociated, not the fraction dissociated.
NCERT: Class 12 Chemistry, Chapter 1, 1.7