The pH of 0.04 M hydrazine solution is 9.7 . Calculate its ionization constant K_(b) and pK_(b).

The pH of 0.04 M hydrazine solution is 9.7 . Calculate its ionization

1.	The pH of 0.04 M hydrazine solution is 9.7 . Calculate its ionization constant K_(b) and pK_(b).
Answer» Solution :`NH_(2)NH_(2)+H_(2)O HARR NH_(2)NH_(3)^(+)+OH^(-)` `PH = 9.7:. Log [H^(+)]=-9.7 = bar(10).3 or [H^(+)]= 1.67 xx 10^(-10)` `:. [OH^(-)]=(K_(w))/([H^(+)])=(10^(-14))/(1.67xx10^(-10))=5.98xx10^(-5)` `K_(b)=([NH_(2)NH_(3)^(+)][OH^(-)])/([NH_(2)NH_(2)])=((5.98xx10^(-5))^(2))/(0.004) = 8.96xx10^(-7)` `pK_(b) = - log K_(b) = - log (8.96 xx 10^(-7))=6.04`