Question

What `%` of the carbon in the `H_(2)CO_(3)-HCO_(3)^(-)` buffer should be in the form of `HCO_(3)^(-)` so as to have a neutral solution? `(K_(a)=4xx10^(-7))`
A. `20%`
B. `40%`
C. `60%`
D. `80%`

Answer 1

`pH=pK_(a)+log(([HCO_(3)^(-)])/([H_(2)CO_(3)]))rArr 7=8-log4+log(([HCO_(3)^(-)])/([H_(2)CO_(3)]))rArr log(([HCO_(3)^(-)])/([H_(2)CO_(3)]))=4`
`%` of carbon in the form of `HCO_(3)^(-)=([HCO_(3)^(-)])/(HCO_(3)[H_(2)CO_(3)])xx100=(4)/(1+4)xx100=80%`