A buffer solution is prepared by mixing `10ml` of `1.0 M` acetic acid & `20 ml` of `0.5 M` sodium acetate and then diluted to `100ml` with distilled water. If the `pK_(a)` of `CH_(3)COOH` is `4.76`. What is the pH of the buffer solution prepared?

Options

A. 5.21
B. 4.76
C. 4.34
D. 5.22

Answer

B

Explanation

The pH of buffer is given by
`pH =pK_(a)+log.(["Salt"])/(["Acid"])`
`pK_(a)=4.76`
Acid`=10mL ` of 1.0 M
Salt`=20mL` of 0.5 M
But total volume is made of 100mL
Hence, [Acid]`=0.1 M`
[Salt]`=0.1 M`
When [Acid]`=` [Salt]
Hence `pH =pK_(a)`
Hence,pH of this buffer will be `4.76 `.