A 11.1 mL sample of vinegar, containing acetic acid, was titrated using 0.520 M NaOH solution. The titration required 27.7 mL of the base. (a) What was the molar concentration of acetic acid in the vinegar? (b) Assuming the density of the vinegar to be 1.1 g/mL, what was the percent (by mass) of acetic acid in the vinegar?