Question 19

It enables resistance to a change in pH.

A buffer functions by resisting significant changes in pH when acids or bases are added to a solution, thus maintaining a relatively stable environment.

A) It permanently binds hydrogen ions.

This option is incorrect because buffers do not permanently bind hydrogen ions. Instead, they facilitate reversible reactions that can absorb or release hydrogen ions to moderate pH changes.

B) It causes the pH of a solution to become neutral.

This statement is misleading as buffers do not necessarily neutralize a solution to a pH of 7. Rather, they maintain the pH within a specific range, which may or may not be neutral.

C) It decreases the pH of the solution.

While buffers can help decrease pH in certain circumstances, this option is incorrect because it implies that buffers solely work to lower pH rather than resist changes in pH overall.

D) It enables resistance to a change in pH.

This is the correct statement, as buffers are specifically designed to minimize fluctuations in pH when acids or bases are introduced to a solution, thus ensuring stability.

Conclusion

The correct answer, D, accurately captures the primary function of a buffer in maintaining pH stability in solutions. Options A, B, and C fail because they either misinterpret the buffer's role or narrow its function to specific pH alterations, rather than emphasizing its overall capability to resist pH changes.