Buffer capacity

Definition

Buffer capacity is a measure of a buffer solution's resistance to pH change when an acid or base is added. It depends on the concentration of the buffer components and their ratio.

5 Must Know Facts For Your Next Test

1. The higher the concentrations of the acidic and basic components of a buffer, the greater its buffer capacity.
2. A buffer has its highest capacity when the pH is equal to the pKa of its acidic component.
3. Buffer capacity decreases significantly when the pH is more than one unit away from the pKa value.
4. It is quantified as the amount of strong acid or base required to change the pH of one liter of buffer solution by one unit.
5. An optimal buffer system should have nearly equal concentrations of both its weak acid and conjugate base.

Review Questions

• What factors influence the buffer capacity of a solution?
• When does a buffer solution have its maximum buffering capacity?
• How is buffer capacity quantitatively measured?

Related terms

pKa: The negative logarithm of the acid dissociation constant (Ka) and indicates the strength of an acid.

Conjugate Base: The species that remains after an acid has donated a proton during a chemical reaction.

Acid-Base Equilibria: The study of reversible reactions between acids and bases in aqueous solutions.