Question

`1 xx 10^(-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`)
A. `4.60`
B. 4.66
C. 4.75
D. 4.8

Answer 1

Correct Answer - B
`{:(CH_(3)COO^(-),+,H^(+),rarr,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`.