52. Solution to Chemistry Problem

2. To determine the iron content in the natural water under study, 25.00 ml of it was treated with hydrogen peroxide and ammonium peroxodisulfate and after adding KNCS, the sample volume was brought to 50.0 ml in a measuring flask with distilled water. The standard solution was prepared by dissolving 0.863 g NH4Fe(SO4)2*12H2O in 100 ml of water. The color equalization method was used for the analysis. For this, 5.50 ml of the standard solution was added to another measuring flask with 20 ml of an aqueous solution of potassium thiocyanate (rhodanide) and its volume was brought to 50.0 ml with distilled water, obtaining a solution with the same intensity as the test one. Determine the iron content in the water under study (mg/l).