The iron in a 6.675-g sample containing some Fe2 O3 is reduced to Fe^2+. The Fe^2+ is titrated w

step 1 For this question, let's start with the given balanced chemical equation. We have 6 F .A .2 plus

The iron in a 6.675-g sample containing some Fe2 O3 is...

The iron in a $6.675-g$ sample containing some $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is reduced to $\mathrm{Fe}^{2+}$. The $\mathrm{Fe}^{2+}$ is titrated with $14.42 \mathrm{~mL}$ of $0.1467 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ in an acid solution. $6 \mathrm{Fe}^{2+}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+14 \mathrm{H}^{+} \longrightarrow$ $6 \mathrm{Fe}^{3+}+2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}(\ell)$ Find (a) the mass of Fe and (b) the percentage of Fe in the samplc.

The iron in a $6.675-g$ sample containing some $\mathrm{Fe}_{2} \mathrm{O}_{3}$ is reduced to $\mathrm{Fe}^{2+}$. The $\mathrm{Fe}^{2+}$ is titrated with $14.42 \mathrm{~mL}$ of $0.1467 \mathrm{M} \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}$ in an acid solution.
$6 \mathrm{Fe}^{2+}+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+14 \mathrm{H}^{+} \longrightarrow$
$6 \mathrm{Fe}^{3+}+2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}(\ell)$
Find (a) the mass of Fe and (b) the percentage of Fe in the samplc.

Key Concepts

Redox Reactions

Redox reactions involve the transfer of electrons between species, where one species is oxidized and another is reduced. Understanding redox reactions is crucial for this problem because the iron in the sample is reduced to Fe²? and then titrated with a strong oxidizing agent, making it necessary to track changes in oxidation state and electron flow.

Titration

Titration is a quantitative analytical technique used to determine the concentration of an analyte by reacting it with a titrant of known concentration. In this context, volumetric analysis through titration helps in determining the amount of iron present by measuring how much titrant is required to react completely with the analyte.

Stoichiometry

Stoichiometry involves using balanced chemical equations to relate the moles of reactants and products. In this problem, the stoichiometric relationship between Fe²? and the dichromate ion is key to calculating the amount of iron present, based on the volume and concentration of the titrant used.

Molarity and Volume Relationship

The concept of molarity, defined as moles of solute per liter of solution, combined with the volume of the solution, is essential for determining the number of moles of titrant involved in the reaction. This relationship allows one to convert measured volumes into quantitative amounts of reactants.

Percentage Composition

Percentage composition is the calculation of the mass percentage of a specific element within a compound or mixture. In this scenario, after determining the moles and mass of iron present, the percentage composition calculation is used to assess the purity or relative content of iron in the sample.

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