Final answer:
To create an effective buffer, select a weak acid and its conjugate base with concentrations close to each other and a pKa near the desired pH range. Utilize the Henderson-Hasselbalch equation to determine the correct ratio for the target pH, and consider buffer capacity, which is higher in solutions with greater concentrations of buffer components.
Step-by-step explanation:
When choosing an acid to make a buffer, certain principles must be considered to ensure that the buffer effectively maintains the desired pH when an acid or base is added. A prime aspect to consider is that a good buffer requires about equal concentrations of an acid and its conjugate base. This balance allows the buffer to neutralize added acids or bases equally, as depicted in figures showing the behavior of acetic acid-acetate ion buffer systems upon the addition of a base or acid. To select a buffer that functions optimally around a specific pH, the pKa of the weak acid should be close to the target pH. For instance, hydrofluoric acid with a pKa of 3.18 is effective in a buffer range around pH 3.18. Using the Henderson-Hasselbalch equation, you can calculate the necessary ratio of conjugate acid to base to achieve a desired pH. Finally, the buffer capacity is also an important factor. A buffer with higher concentrations of its components can neutralize more added acid or base without a significant change in pH. For example, a 1.0 M acetic acid and 1.0 M sodium acetate buffer has a greater capacity than a 0.10 M acetic acid and 0.10 M sodium acetate buffer, even though they may have the same initial pH.