Chemistry - Redox Reactions Question with Solution | TestHub
A 3.0 g sample containing , and an inert impure substance is treated with excess of solution in the presence of dilute . The entire iron is converted to along with the liberation of iodine. The resulting solution is diluted to 100 ml. A 20 ml of dilute solution requires 10.0 ml of 0.5 M - solution to reduce the iodine present. A 50 ml of the diluted solution, after complete extraction of iodine, requires 12.0 ml of 0.25 M - solution in dilute medium for the oxidation of . The percentage of in the original sample is
Answer:
Solution:
in 20 ml = (10×0.5)/2 = 2.5 mmol, total = 12.5 mmol, so total = 25 mmol. Total in 50 ml = 5×12×0.25 = 15 mmol, total Fe = 30 mmol. With a = mmol , b = mmol : a+b = 12.5, 3a+2b = 30 a = 5, b = 7.5 mmol. Mass = = 1200 mg = 1.2 g; % = 1.2/3.0×100 = 40%. Ans 0040.
