Question

Calculate the ratio of the concentrations of acetate and acetic acid required in a buffer system of pH 5.30.

(a) 3.2

(b) 3.3

(c) 3.4

(d) 3.5

I have been asked this question during an interview.

This interesting question is from Buffering against pH changes in Biological Systems topic in chapter Water Basics of Biochemistry

Answer 1

The correct choice is (d) 3.5

For explanation: pH = pKa + log [acetate]/[acetic acid]

log [acetate]/[acetic acid] = pH – pKa

                            = 5.30 – 4.76 = 0.54

   [acetate]/[acetic acid] = antilog 0.54 = 3.5.