Question

Use the Ka values for weak acids to identify the best components for preparing buffer solutions with the given pH values.

Name Formula Ka
Phosphoric acid H3PO4 7.5 x 10^-3
Acetic acid CH3COOH 1.8 x 10^-5
Formic acid HCOOH 1.8 x 10^-4

pH 1.9 =_________
pH 5.0 = ________
pH 3.9= ________

Answer 1

pH= 1.9 then
`H_(3) PO_(4)`

pH = 5.0 ,
`CH_(3) COOH`

pH = 3.9 , HCOOH

As we know range left
`pH= pKa+/- 1`