28. Solving a chemistry problem

3. To determine SO3 in cement, a sample of cement weighing 0.85 (g) was dissolved, filtered, and the solution was passed through a chromatographic column containing a cation exchanger in the H-form. The eluate and washing waters were collected in a 100 ml volumetric flask and made up to the mark with water. Then 25 ml of the resulting solution was titrated potentiometrically on an autotitrator with a 0.1 M NaOH solution, the volume of sodium hydroxide used for titration was 1.05 ml. Determine the percentage of SO3 in cement.