47. Solving a chemistry problem

4. A sample of novocaine hydrochloride C13H20N2O2∙HCl, contaminated with impurities, weighing 1.0350 g was dissolved in water and 250.0 ml of solution was obtained. For titration of an aliquot of 10.00 ml in the presence of hydrochloric acid and an excess of potassium bromide, 3.05 ml of a 0.04863 mol/l solution of sodium nitrite went. Calculate the mass fraction of novocaine hydrochloride in the sample