NEET2009ChemistryElectrochemistryActual
The equivalent conductance of M 32 solution of a weak monobasic acid is 8.0 ~mho~ cm ^2 and at infinite dilution is 400 ~mho~ cm ^2 . The dissociation constant of this acid is
Options
- A1.25 10⁻⁵
- B1.25 10⁻⁶
- C6.25 10⁻⁴
- D1.25 10⁻⁴
Correct answer
A. 1.25 10⁻⁵
Step-by-step solution
Degree of dissociation, = ^c ^ where, ^c and ^ are equivalent conductances at a given concentration and at infinite dilution respectively. = 8.0 400 =2 10⁻² From Ostwald's dilution law (for weak monobasic acid) aligned K _ a & = C ^2 (1- ) or & C ^2 & = 1 32 (2 10⁻² )^2 or & =1.25 10⁻⁵ aligned