Advanced Placement (AP) Chemistry Practice Exam

Which of the following is a common application of buffer solutions?

1. To increase the temperature of a reacting system.

2. To stabilize the pH of biological fluids.

3. To promote the precipitation of salts.

4. To accelerate chemical reaction rates.

The correct answer is: To stabilize the pH of biological fluids.

Buffer solutions play a critical role in maintaining a stable pH in various environments, particularly in biological systems. Biological fluids, such as blood and intracellular fluid, rely on buffers to resist changes in pH that can occur due to metabolic processes or external influences. For instance, the bicarbonate buffer system in blood helps to regulate pH levels, ensuring that they remain within a narrow range necessary for proper physiological function. This stability is crucial since even minor fluctuations in pH can disrupt enzyme activity and overall cellular function. The other options do not accurately represent common applications of buffer solutions. Increasing temperature is typically not a function of buffers, while promoting precipitation of salts involves adjusting conditions to favor solid formation rather than maintaining pH. Similarly, accelerating reaction rates often pertains to the presence of catalysts and does not inherently involve buffers, which primarily focus on pH stabilization. Thus, stabilizing the pH of biological fluids stands out as a key application of buffer solutions.