44. Solving a chemistry problem

292. A weighing of 0.5000 g of nahcolite containing sodium bicarbonate was dissolved in water in a volumetric flask with a capacity of 250.0 cm3. To 100.0 cm3 of the resulting solution was added 50.0 cm3 of a hydrochloric acid solution with a titer of 0.003646 g/cm3. After removal of carbon dioxide, 19.6 cm3 of 0.1351 N potassium hydroxide solution was used for titration of excess acid. Calculate the mass fraction of impurities in the mineral.