31. Solving a chemistry problem

32. A sample of steel weighing 1.0000 g was dissolved in acids, chromium contained in the steel was oxidized to Cr2O72- and 15.00 ml of 0.2500 M Mohr´s salt solution was added to the resulting solution. The excess of Mohr´s salt was titrated with 0.1000 M (1/5 KMnO4) solution of potassium permanganate, using 25.50 ml. Calculate the mass fraction (%) of chromium (52.0) in steel.