An iron ore sample weighing 0.5562 g is dissolved HCl (aq), and the iron is obtained as Fe2 in solution. This solution is then titrated with 28.72 mL of 0.04021 M K2Cr2O7 (aq). What is the percent by mass iron in the ore sample

Explanation:

Hello,

In this case, we could considering this as a redox titration:

Thus, the balance turns out (by adding both hydrogen ions and water):

Thus, by stoichiometry, the grams of Fe+2 ions result:

Finally, the mass percent is:

Best regards.