A 5.00-g sample of vinegar is titrated with 0.108 MNaOH. If the vinegar requires 39.1 mL of the NaOH solution for complete reaction, what is the mass percentage of acetic acid, HC2H3O2, in the vinegar? The reaction is HC2H3O2 (aq) + NaOH(aq) à NaC2H3O2 + H2O(l)