MHT CET202521 Apr 2025Evening ShiftChemistryIonic EquilibriumActual
Which from following formulae is used to find the [ OH ⁻ ] ion concentration of a weak monoacidic base?
Options
- AK _ b c
- BK _ b c
- CK_b c
- DK_b
Correct answer
B. K _ b c
Step-by-step solution
A weak monoacidic base BOH of initial concentration c dissociates as BOH B ⁺ + OH ⁻ . At equilibrium, [ OH ⁻] = cx and [ BOH ] = c(1-x) , where x is the degree of dissociation. The base dissociation constant is K_b = (cx)(cx) c(1-x) = cx^2 1-x . For weak bases, x 1 , so 1 - x 1 , simplifying to K_b cx^2 and x K_b c . Substituting gives [ OH ⁻] = c K_b c = K_b c . B