40. Solving a chemistry problem

17. Quantitative determination of the active substance in the dosage form "Coated tablets of ibuprofen 0.2 g" is carried out according to the method of VFS 42-1187-82: 5 tablets crushed into powder (average tablet weight 0.482 g) are quantitatively transferred into a volumetric flask with a capacity of 50 ml and dissolved in 40 ml of thymol blue neutralized ethanol, the volume of the solution was adjusted to the mark with the same solvent. To 10 ml of the resulting solution add 5 drops of thymol blue and titrate with 0.1 M sodium hydroxide solution until a gray-blue color is obtained. The content of ibuprofen (M.m. = 206.3) in one tablet should be from 0.19 to 0.21. Draw a conclusion about the quality of the drug form if 9.93 ml of 0.1 M sodium hydroxide solution was used for titration. Justify the choice of method, write the equations of chemical reactions.