A buffer solution contains 0.1 mole of sodium acetate dissolved in `1000 cm^(3)` of 0.1 M acetic acid. To the above buffer solution, 0.1 mole of sodium acetate is further added and dissolved. The pH of the resulting buffer is

Options

A. `pK_(a)-log2`
B. `pK_(a)`
C. `pK_(a)+2`
D. `pK_(a)+log2`

Answer

D

Explanation

`pH=pK_(a)+"log"(["Salt"])/(["Acid"])`
`["Salt"]=(0.1+0.1)/(1000" mL")=(0.2)/(1)=0.2`
`["Acid"]=(0.1)/("1000 mL")=(0.1)/(1)=0.1`
`pH=pK_(a)+log2`.