`1xx10^(-3)`mole of HCl is added to a buffer solution made up of 0.01 M acetic acid and 0.01 M sodium acetate. The final pH of the buffer will be (given, `pK_a` of acetic acid is 4.75 at `25^@` C)

Options

A. `4.60`
B. `4.66`
C. `4.75`
D. `4.8`

Answer

B

Explanation

`{:(CH_(3)COO^(-), +,H^(+) ,to, CH_(3)COOH),(0.01,,0.001,,0.01),(0.01-0.001,,,,0.01+0.001),(=0.009,,,,=0.011):} `
`pH = pKa +log . (["salt"])/(["acid"]) = 4.75 +log. (0.009)/(0.011) = 4.66`