Question

1. What is the change in pH after the strong acid was added to the buffer solution, relative to the pH of the buffer solution?

2. What is the change in pH when the strong acid was added to DI water, relative to the pH of pure DI water? How is this significant in relation to the titration?
3. Does this show that buffer solutions resist a change in pH when a small amount of a strong acid or base is added to the solution?

Answer 1

Buffer solutions have the ability to resist changes in pH when small quantities of strong acids or bases are added, due to the presence of weak acids or bases and their conjugates that neutralize additional acids or bases.

Step-by-step explanation:

The change in pH after the addition of a strong acid to a buffer solution is relatively small compared to the change in pH after the strong acid is added to deionized (DI) water. This is because a buffer contains a weak acid or base along with its conjugate, which helps to neutralize added acids or bases, thus resisting changes in pH.

For example, if we add 5.00 mL of 1.00 M HCl to an unbuffered solution at pH 3.95, the pH drops drastically to 1.32. However, in a buffered solution, the pH might change from 3.95 to only 3.70 after adding the same amount of HCl, demonstrating the buffer's ability to maintain pH stability.

Indeed, this shows that buffer solutions can effectively resist changes in pH when a small amount of a strong acid or base is added to the solution. This property is critical in various applications, such as biological systems and chemical reactions where maintaining a constant pH is necessary.