Final answer:
The question deals with the preparation of a buffer solution at pH 9.0 using NaOH and histidine at a specific total concentration. It requires an understanding of the behavior of buffers and their capacity to maintain pH, as well as the concept of limiting reagents in the formation of the buffer.
Step-by-step explanation:
The question involves understanding how to make a buffer solution with a specific pH, which in this case is pH 9.0 using NaOH and histidine. To prepare a buffer, it is critical to mix a weak acid or a weak base with its conjugate salt in such a way that the solution can resist changes in pH upon the addition of small amounts of acid or base. In the scenario presented, NaOH (a strong base) is used to adjust the pH of the histidine solution. Depending on the amounts of NaOH and histidine used, one of them could be the limiting reagent, or both could be present in excess. If the correct proportion is not achieved, the solution could fail to act as a buffer.
A buffer's ability to maintain pH stems from the presence of a weak acid-base conjugate pair. As the concentration of this conjugate pair increases in the solution, generally the buffer capacity also increases, which means even the addition of relatively large amounts of a strong acid or base (such as NaOH) would only cause a small change in pH. This illustrates how important the concentration of the buffer components is in determining the buffer's capacity.