Buffer Solutions

Flashcards summarizing the key aspects of buffer solutions, their chemistry, preparation, and applications.

What is a Buffer solution?

An aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid that resists changes in pH when small amounts of acid or base are added.

How does a buffer solution resist changes in pH?

When H+ are added to the solution the equilibrium moves to the left. When OH- are added the equilibrium moves to the right as H+ are removed in the reaction, thus some of the added reagent is consumed in shifting the equilibrium.

What is the Henderson-Hasselbalch equation?

pH = pKa + log ([conjugate base or salt]/[acid])

How do you make a buffer solution at a specific pH?

By using the Henderson-Hasselbalch equation: pH = pKa + log [A-]/[HA]

What two things are important when making a buffer solution at a specific pH?

Determine the pKa of the weak acid and the desired ratio of the concentration of the acid and its conjugate base (or salt).

What is Buffer capacity?

A measure of the efficiency of a buffer in resisting changes in pH, indicating the amount of acid or base that can be added before the buffer loses its ability to resist the change in pH.

On what two things does buffer capacity depend?

How close the pH of the buffer is to the pKa (should be within 1-2 pH units) and the total concentration of the buffer.

For what are buffer solutions useful?

Chemical manufacturing, biochemical processes, and maintaining optimal conditions for enzymes.

What buffer system is present in blood plasma?

A buffer of carbonic acid (H2CO3) and bicarbonate (HCO3 −) is present in blood plasma.

In what industrial processes are buffer solutions used?

Fermentation processes, setting correct conditions for dyes in coloring fabrics, chemical analysis, and calibration of pH meters.