Ferrochrome is an alloy made from iron and chromium. Ferrochrome may be dissolved in dilute sulfuric acid, giving a mixture of $\text{FeSO}_4$ and $\text{Cr}_2(\text{SO}_4)_3$. The $\text{FeSO}_4$ reacts with $\text{K}_2\text{Cr}_2\text{O}_7$ in acid solution according to the equation below. $14\text{H}^+ + 6\text{Fe}^{2+} + \text{Cr}_2\text{O}_7^{2-} \rightarrow 2\text{Cr}^{3+} + 6\text{Fe}^{3+} + 7\text{H}_2\text{O}$ If $1.00\ \text{g}$ of ferrochrome is dissolved in dilute sulfuric acid, and the solution produced is then titrated, $13.1\ \text{cm}^3$ of $0.100\ \text{mol dm}^{-3}$ $\text{K}_2\text{Cr}_2\text{O}_7$ is needed for complete reaction. What is the percentage by mass of Fe in the ferrochrome sample?
- A1.22
- B4.39
- C12.2
- D43.9