3. Molarity is only one of many ways to express concentrations. Another is percent mass per volume or % (m/v). For example, vinegar usually contains about 5% (m/v) acetic acid (5g acetic acid/100 mL vinegar). Calculate the molarity of acetic acid in a vinegar that is 5.5% (m/v) acetic acid. The molecular formula of acetic acid is C2H402.