Calculate the pH of 0.1 M solution of (i) `NaHCO_(3)` , (ii) `Na_(2)HPO_(4)` and (ii) `NaH_(2)PO_(4)`. Given that :
`CO_(2)+H_(20O Leftrightarrow H^(+) + HCO_(3)^(-)`
`K_(1)=4.2 xx 10^(-7) M`
`HCO_(3)^(-) Leftrightarrow H^(+)+CO_(3)^(2-)`,
`K_(2)=4.8 xx 10^(-11)M`
`H_(3)PO_(4) Leftrightarrow H^(+) +H_(2)PO_(4)^(-)`,
`K_(1)=7.5 xx 10^(-3)M`
`H_(2)PO_(4)^(-) Leftrightarrow H^(+)+HPO_(4)^(2-)`,
`K_(2)=6.2 xx 10^(-8)M`
`HPO_(4)^(2-) Leftrightarrow H^(+)+PO_(4)^(3-)`,
`K_(3)=1.0 xx 10^(-12)M`

Answer

8.35,9.60,4.66