Posted by Amanda on .
You want to prepare a pH=4.50 using sodium acetate and glacial acetic acid. You have n hand 300 mL of 0.100 M sodium acetate. How many grams of glacial acetic acid should you add to prepare the buffer? (Ka of acetic acid is 1.8e-5 at: 25 degrees Celsius)
Use the Henderson-Hasselbalch equation.
4.5 = 4.74 + log(b)/(a)
Solve for B/A.
You know acid is 300 mL x 0.1M = 30 millimoles.
Solve for base in millimoles. I would then convert to mols and from the to grams.
Finally, put all of that back into the equation to check that you really do get a pH of 4.5.