Answer
3.3mL of acetic acid for 1 liter of vinegar.
Work Step by Step
pH of vinegar must be 3.
What is the volume of acetic acid required to make a pH 3?
Henderson-Hasselbalch equation, $pH =pK_{a} +log([A]/[HA])$
pK_{a} of acetic acid = 4.76
3 = 4.76 +log([A]/[HA])
log([A]/[HA]) =1.76
[A]/[HA] =$10^{1.76}$ =58
[HA] =58 [A]
[A] = [H]= $10^{-pH} =10^{-3}$ =
[HA] =58 [A] = 58 $\times10^{-3}$ =0.058 M
Molecular weight of acetic acid = 60g/mol
Density =1.049 g/mL
Concentration of acetic acid = Density /molecular weight = 1.049 / 60 =0.017 mol/mL
Volume of acetic acid to prepare 1 L of vinegar = [HA]/ Concentration = 0.058/0.017 = 3.3 mL
