Question

To measure the amount of iron in a certain type of iron ore, an analytical chemist dissolves a sample in strong acid and titrates it to the endpoint with of potassium permanganate solution. The balanced chemical equation for the reaction is:

Answer 1

Answer:

$\% Fe=11.4\%$

Explanation:

Hello!

In this case, for the described chemical reaction, we find it is:

$8H^+(aq)+5Fe^{2+}(aq)+MnO_4^-(aq)\rightarrow 5Fe^{3+}(aq)+Mn^{2+}(aq)+4H_2O(l)$

Because it says that the iron is dissolved in a strong acid which provides addition hydrogen ions to the reaction media. Thus, for the questions attached on the figure we find:

- This a REDOX reaction because we see iron is being oxidized from 2+ to 3+ and manganese reduced from +7 to +2.

- Since it is a redox reaction and the oxidized species is that undergoing an oxidation number increase, we evidence iron goes from +2 to +3, which means iron is the oxidized species.

- In this case, for the used 59.2 mL (0.0592 L) of the 0.2000 M solution of potassium permanganate, we can compute the consumed grams of iron via stoichiometry including the 5:1 mole ratio between them in the chemical reaction:

$m_{Fe^{2+}}=0.0592L*0.2000\frac{molMnO_4^-}{L}*\frac{5molFe^{2+}}{1molMnO_4^-} *\frac{55.85gFe^{2+}}{1molFe^{2+}} \\\\m_{Fe^{2+}}=3.31gFe^{2+}$

It means that the percent of iron in that sample is:

$\% Fe=\frac{3.31g}{29.00g} *100\%\\\\\% Fe=11.4\%$

Best regards.