Ascorbic acid (vitamin c) is a  diprotic acid of molecular weight 176 g/mol. A sample of vitamin  supplement was analyzed by titrating a 0.1g sample dissolved in water  with 0.02 M NaOH. A volume of 15.2 ml of the base was required to  completely neutralize the ascorbic acid. What was the mass percent of  ascorbic acid in the sample?