The metal content of iron in ores can be determined by a redox procedure in which the sample is first oxidized with Br2 to convert all the iron to Fe3+ and then titrated with Sn2+ to reduce the Fe3+ to Fe2+. The balanced equation is: What is the mass percent Fe in a 0.1875 g sample of ore if 13.28 mL of a 0.1015 M Sn2+ solution is needed to titrate the Fe3+?

Verified step by step guidance

1. Identify the balanced chemical equation for the reaction: \[ \text{Fe}^{3+} + \text{Sn}^{2+} \rightarrow \text{Fe}^{2+} + \text{Sn}^{4+} \].
2. Calculate the moles of \( \text{Sn}^{2+} \) used in the titration using the formula: \( \text{moles} = \text{Molarity} \times \text{Volume (L)} \).
3. Use the stoichiometry of the balanced equation to determine the moles of \( \text{Fe}^{3+} \) that reacted. Since the ratio is 1:1, the moles of \( \text{Fe}^{3+} \) will be equal to the moles of \( \text{Sn}^{2+} \).
4. Calculate the mass of iron (Fe) using the moles of \( \text{Fe}^{3+} \) and the molar mass of iron (55.85 g/mol).
5. Determine the mass percent of iron in the ore sample using the formula: \( \text{Mass percent} = \left( \frac{\text{mass of Fe}}{\text{mass of ore sample}} \right) \times 100 \).

Key Concepts

Redox Reactions

Redox reactions involve the transfer of electrons between two species, resulting in oxidation and reduction processes. In this context, Br2 oxidizes Fe to Fe3+, while Sn2+ reduces Fe3+ back to Fe2+. Understanding these electron transfer processes is crucial for analyzing the stoichiometry of the reaction and calculating the amount of iron present in the sample.

Titration

Titration is a quantitative analytical technique used to determine the concentration of a solute in a solution. In this case, the titration of Fe3+ with Sn2+ allows for the calculation of the amount of iron in the ore sample. The volume and molarity of the titrant (Sn2+) used in the reaction are essential for determining the moles of Fe3+ and, subsequently, the mass percent of iron in the sample.

Mass Percent Calculation

Mass percent is a way to express the concentration of a component in a mixture, calculated as the mass of the component divided by the total mass of the mixture, multiplied by 100. To find the mass percent of Fe in the ore sample, one must first determine the mass of Fe from the titration data and then relate it to the original mass of the ore sample. This concept is fundamental for expressing the results of the analysis in a meaningful way.