9. Solving a chemistry problem

56. The solution of ammonium sulfate in the device for distillation of ammonia is treated by heating with an excess of sodium hydroxide solution; ammonia is absorbed by 50 ml of 0.2 N sulfuric acid solution. The resulting solution was titrated with 22.50 ml of 0.25 M sodium hydroxide solution. Calculate the mass of ammonium sulfate in the analyzed sample.