87. Solving a chemistry problem

5. Acetic anhydride was added to a weighed portion of a 1.000 g solution containing ethylene glycol and neutralized with a NaOH solution to phenolphthalein. To saponify the resulting ester, 25.00 ml of NaOH solution [T(NaOH) = 0.04020] was introduced:

The mixture was boiled and after cooling, the excess alkali was titrated with 10.20 ml of HCl solution with [T(HCI) = 0.03798]. Calculate the mass fraction (%) of ethylene glycol (M = 62.07 g/mol) in solution.