Summary 3

A buffer is able to resist pH change because the two components (conjugate acid and conjugate base) are both present in appreciable amounts at equilibrium and are able to neutralize small amounts of other acids and bases (in the form of H3O+ and OH-) when they are added to the solution.

This buffering action can be seen in the titration curve of a buffer solution.

• If acid is added:

F− (aq) +H3O+ (aq) ⇌ HF (aq) +H2O (l)

In this reaction, the conjugate base, F-, will neutralize the added acid, H3O+, and this reaction goes to completion, because the reaction of F- with H3O+ has an equilibrium constant much greater than one.