Chemistry 9701 · AS & A Level · Electrochemistry

Electrochemistry — practice question

When acidified dichromate(VI) ions, $\text{Cr}_2\text{O}_7^{2-}$, react with aqueous $\text{Fe}^{2+}$ ions, the dichromate(VI) ions are reduced to $\text{Cr}^{3+}$ ions. Which equation correctly represents this reaction?

  • A$ ext{Cr}_2 ext{O}_7^{2-} + ext{Fe}^{2+} + 14 ext{H}^+ ightarrow 2 ext{Cr}^{3+} + ext{Fe}^{3+} + 7 ext{H}_2 ext{O}$
  • B$ ext{Cr}_2 ext{O}_7^{2-} + 2 ext{Fe}^{2+} + 14 ext{H}^+ ightarrow 2 ext{Cr}^{3+} + 2 ext{Fe}^{3+} + 7 ext{H}_2 ext{O}$
  • C$ ext{Cr}_2 ext{O}_7^{2-} + 3 ext{Fe}^{2+} + 14 ext{H}^+ ightarrow 2 ext{Cr}^{3+} + 3 ext{Fe}^{3+} + 7 ext{H}_2 ext{O}$
  • D$ ext{Cr}_2 ext{O}_7^{2-} + 6 ext{Fe}^{2+} + 14 ext{H}^+ ightarrow 2 ext{Cr}^{3+} + 6 ext{Fe}^{3+} + 7 ext{H}_2 ext{O}$

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