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Chapter 2: Problem 16

\(14 \mathrm{H}^{+}(a q)+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+3 \mathrm{Ni}(s) \rightarrow\) \(2 \mathrm{Cr}^{3+}(a q)+3 \mathrm{Ni}^{2+}(a q)+7 \mathrm{H}_{2} \mathrm{O}(l)\) In the above reaction, a piece of solid nickel is added to a solution of potassium dichromate. Which species is being oxidized and which is being reduced? \(\quad\) Oxidized \(\quad\) Reduced (A) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q) \quad \mathrm{Ni}(s)\) (B) \(\mathrm{Cr}^{3+}(a q) \quad \mathrm{Ni}^{2+}(a q)\) (C) \(\mathrm{Ni}(s) \quad \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)\) (D) \(\mathrm{Ni}^{2+}(a q) \quad \mathrm{Cr}^{3+}(a q)\)

Short Answer

Expert verified
The species getting oxidized is Ni and the species getting reduced is Cr2O72-. Hence, the correct option is (C) Ni, Cr2O72-.

Step by step solution

01

Identifying Oxidation

First, identify the oxidation reaction. The oxidation is a process in which an atom loses its electrons. Compare the Ni atoms before and after the reaction. Before the reaction, the Ni s is neutral, but after the reaction, it forms Ni2+ aq, indicating that it has lost two electrons. Thus, Ni is the species getting oxidized.
02

Identifying Reduction

Next, identify the reduction reaction. Reduction is a process in which an atom gains electrons. Compare the Cr2O72- molecules before and after the reaction. Before the reaction, each Cr atom had an average oxidation state of +6 but after the reaction, each Cr forms Cr3+ aq, meaning its oxidation state decreases to +3. Therefore, it has gained electrons and Cr2O72- is the species getting reduced.

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Most popular questions from this chapter

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