Question

How much sodium acetate should be added to a 0.1 M solution of `CH_(3)COOH` to give a solution of pH = 5.5 (`pK_(a)` of `CH_(3)COOH = 4.5`)
A. 0.1 M
B. 0.2 M
C. `1.0 M`
D. `10.0 M`

Answer 1

Correct Answer - C
`pH = pK_(a) + log.(["Salt"])/("Acid") , 5.5 = 4.5 + log.(["Salt"])/("Acid")`
`log.(["Salt"])/("Acid") = 5.5 - 4.5 = 1`
`(["Salt"])/(0.1) = "antilog 1" = 10, ["Salt"] = 1` .