The pH of 0.05 M aqueous solution of diethylamine is 12.0. Calculate its `K_b` .

Explanation

`(C_(2)H_(5))_(2)NH+H_(2)O hArr(C_(2)H_(5))_(2)NH_(2)^(+)+OH^(-)`
As `pH = 12, :. [H^(+)]=10^(-12)M or [OH^(-)]=10^(-2)M, [(C_(2)H_(5))_(2)NH]=0.05-0.01 = 0.04 M `
`K_(b) = ([(C_(2)H_(5))_(2)NH_(2)^(+)][OH^(-)])/([(C_(2)H_(5))_(2)NH]) = (10^(-2)xx10^(-2))/(0.04)=2.5xx10^(-3)" " {[C_(2)H_(5))_(2)NH_(2)^(+)]=[OH^(-)]}`