Final answer:
Calculating the ΔpH for the addition of NaOH to a buffer requires knowledge of the buffer's component concentrations. Without these, a precise numerical answer is not possible, but we can state that the pH increase will be minimal due to the buffer's capacity to resist changes in pH.
Step-by-step explanation:
The question asks us to calculate the change in pH, or ΔpH, when a buffered solution containing aniline and aniline hydrochloride is treated with NaOH. A buffer solution is designed to resist changes in pH when small amounts of acid or base are added. The initial pH of the solution is 5.75.
To solve this problem, we must understand the concept of buffer action, which follows the Henderson-Hasselbalch equation. However, without the concentrations of the aniline and aniline hydrochloride, precise calculations are not possible. Still, we can say that the addition of a strong base (NaOH) to a buffer will convert some of the anilinium ions (C₆H₅NH₃⁺) into aniline (C₆H₅NH₂), essentially using up some of the buffer's capacity to neutralize added base. This process will cause a slight increase in pH but significantly less than it would if no buffer were present.
Since the precise concentrations of the components of the buffer are not given, a precise numerical answer cannot be provided here. Generally, a well-chosen buffer would show only a tiny change in pH upon the addition of 0.397 g of NaOH in 1.25 L of buffer solution.