Question

What will happen to the pH of a buffer if acid/base ratio is increased by 100?

Answer 1

Answer:

It will decrease by 2 units.

Explanation:

The Henderson-Hasselbalch equation for a buffer is

pH = pKa + log(base/acid)

Let's assume your acid has pKa = 5.

(a) If the base: acid ratio is 1:1,

pH(1) = 5 + log(1/1) = 5  + log(1) = 5 + 0 = 5

(b) If the base: acid ratio is 1:100,

pH(2) = 5 + log(1/100) = 5  + log(0.01) = 5 - 2 = 3

(c) Difference

ΔpH = pH(2) - pH(1) = 5 - 3 = -2

If you increase the acid:base ratio to 100:1, the pH will decrease by two units.