Iron(II) ion reacts with water to a small extent by a hydrolysis reaction: Kc 2 x 107 Sulfuric acid was added to the stock Fe+ solution to prevent this hydrolysis. How would you final result for the % iron change if you forgot to add the 5 drops of 6M H2SO4 to your iron unknown? Explain. (assume FeOH does not react with o-phen) Solution Hydrolysis of Fe2+ is prevented by the addition of 5 drops of 6 M H2SO4. If we forgot to add this H2SO4, the % iron found would be lower than the expected value as the hydrolyzed Fe2+ would not form the o-phen complex and fails to contribute to the final absorbance value. Absorbance is directly proportional to concentration of Fe-phen complex in solution .