138. Задачка по химии №013 834

97. For chromium analysis, 1.0170 g of steel was dissolved and oxidized. For the reduction of the resulting chromic acid, 40.00 cm3 of Mohr´s salt solution was taken. For titration of its excess, 5.02 cm3 of a KMnO4 solution with C (1/5 KMnO4) = 0.02394 mol / dm3 were consumed. 10.00 cm3 of Mohr´s salt is equivalent to 9.63 cm3 of KMnO4 solution. Determine the mass fraction of chromium in a steel sample.