The pH of an acetic acid ` + ` sodium acetate buffer is given by `pH = pK_(a) + log . "[Salt]"/"[Acid]" " where " K_(a)` of acetic acid ` = 1.8 xx 10^(-5)`
If [Salt] = [Acid] ` = 0.1` M, then the pH of the solution would be about

Options

A. 7
B. 4.7
C. 5.3
D. 1.4

Answer

B

Explanation

`["Salt"] = 0.1 M, ["Acid"] = 0.1 M`
`K_(a) = 1.8 xx 10^(-5) , pH = -logK_(a) + log.(["Salt"])/(["Acid"])`
`= -log 1.8 xx 10^(-5) + log.(0.1)/(0.1) = -log 1.8 xx 10^(-5)`
`pH = 4.7`.