We’re asked to determine which of the following solutions to use in order to prepare a buffer with a pH of 3.60.
Recall that a buffer can be composed of the following:
• weak base and its conjugate acid
• weak acid and its conjugate base
• weak acid and a strong base
▪ concentration of weak acid > concentration of strong base
• weak base and a strong acid
▪concentration of weak base > concentration of strong acid
Also, recall that we can solve for the pH of a buffer solution using the Henderson-Hasselbalch equation:
Therefore, we have to look for a combination of solutions that make a buffer with a pH close to 3.60.
You have to prepare a pH 3.60 buffer, and you have the following 0.10 M solutions available: HCOOH, CH3COOH, H3PO4, HCOONa, CH3COONa, and NaH2PO4.
Which solutions would you use?