Question

A buffer solution contains `0.1` mol each of `NaCH_(3)COO` and `CH_(3)COOH`. On diluting the solution to double its volume, the pH of the solution
A. will because half
B. will remain unchanged
C. will be doubled
D. cannot be predicted

Answer 1

Correct Answer - B
According to the Henderson equation, pH of the acidic buffer is given as
`pH = pK_(a)+"log" (["salt"])/(["acid"])`
On dilution (addition of more of solvent, `H_(2)O`), the value of `K_(a)` does not change and the ratio `["salt"]//["acid"]` remains unchanged as both `["salt"]` and `["acid"]` will change on dilution.