Advanced Placement (AP) Chemistry Practice Exam

Why is the Henderson-Hasselbalch equation essential for understanding buffer solutions?

1. It quantifies the temperature changes in buffer systems.

2. It predicts how buffers will respond to acid or base addition.

3. It determines the solubility of buffer components.

4. It calculates the dilution of buffer solutions.

The correct answer is: It predicts how buffers will respond to acid or base addition.

The Henderson-Hasselbalch equation is crucial for understanding buffer solutions because it provides a mathematical relationship that predicts how buffers respond to the addition of acids or bases. Buffer solutions consist of a weak acid and its conjugate base (or a weak base and its conjugate acid), and they are designed to maintain a relatively stable pH when small amounts of strong acid or strong base are introduced. The equation is expressed as: pH = pKa + log([A⁻]/[HA]), where pH is the measure of acidity, pKa is the negative logarithm of the acid dissociation constant, [A⁻] is the concentration of the conjugate base, and [HA] is the concentration of the weak acid. By utilizing this equation, one can determine how the pH of the solution will change when acids or bases are added, providing insight into the buffer's ability to resist fluctuations in pH. This predictive capacity is fundamental for various applications in chemistry and biochemistry, such as in metabolic processes or laboratory buffer preparations. The other options do not accurately describe the role of the Henderson-Hasselbalch equation. It does not quantify temperature changes, determine solubility, or calculate the dilution of buffer