Phenol `(C_(6)H_(5)OH,K_(a)=1.3xx10^(-10))` is a weak acid used in mouth washes and pyridine `(C_(5)H_(5)N,K_(b)=1.8xx10^(-9))` is a weak base used as a solvent. Calculate the value of `K_(n)` for neutralization of phenol by pyridine. Does the neutralization reaction proceed very far towards completion ?

Explanation

`C_(6)H_(5)OH+C_(5)H_(5)N hArr C_(6)H_(5)O^(-)+C_(5)H_(5)NH^(+)`
`K_(H)= (K_(w))/(K_(a)xxK_(b))= (10^(-14))/(1.3xx10^(-10xx1.8xx10^(-9))`
`=4.273xx10^(4)`
`K_(n)=(1)/(K_(H))=(1)/(4.273xx10^(4))=2.34xx10^(-5)`
`K_(n)` being small and thus neutralisation does not proceed very far towards completion.