We’re asked to determine how to make a sodium acetate/acetic acid buffer (CH3CO2Na / CH3CO2H) with a pH of 4.74 between 3 options, given that acetic acid has a pKa of 4.74.
Since the solution is a buffer, we can use the Henderson-Hasselbalch equation:
In the solution, we need to identify the weak acid and its conjugate base.
Acetic acid has a pKa of 4.74. A sodium acetate/ acetic acid buffer (CH3CO2Na / CH3CO2H) with a pH of 4.74 can be made by:
a. Combining 0.10 mole of CH3CO2H with 0.10 mole of CH3CO2Na in water
b. Combining 0.20 mole of CH3CO2H with 0.20 of NaOH in water
c. Combining 0.20 mole of CH3CO2H with 0.10 mole of NaOH in water