Multiple Choice
Given the following standard reduction potentials:A^{2+} + 2e^- → A(s)E^ext{°} = -0.50ext{ V}B^{+} + e^- → B(s)E^ext{°} = +0.20ext{ V}Which species is the stronger oxidizing agent under standard conditions?
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20. Electrochemistry
Standard Reduction Potentials
Multiple Choice
In the following reaction identify the oxidizing agent and the reducing agent:
Cr2O72- + 6 Fe2+ + 14 H+ → 2 Cr3+ + 6 Fe3+ + 7 H2O
A
Oxidizing Agent:Fe, Reducing Agent:H
B
Oxidizing Agent:Fe, Reducing Agent:Cr
C
Oxidizing Agent:Cr, Reducing Agent:Fe
D
Oxidizing Agent:H, Reducing Agent:Fe
Verified step by step guidance1
Understand the concept of oxidation and reduction: Oxidation involves the loss of electrons, while reduction involves the gain of electrons. An oxidizing agent is a substance that gains electrons and is reduced, whereas a reducing agent is a substance that loses electrons and is oxidized.
Examine the oxidation states of the elements involved in the reaction. For example, in the dichromate ion \( \text{Cr}_2\text{O}_7^{2-} \), chromium typically has an oxidation state of +6. In \( \text{Cr}^{3+} \), chromium has an oxidation state of +3.
Determine the change in oxidation states for each element. Chromium goes from +6 in \( \text{Cr}_2\text{O}_7^{2-} \) to +3 in \( \text{Cr}^{3+} \), indicating a reduction. Iron goes from +2 in \( \text{Fe}^{2+} \) to +3 in \( \text{Fe}^{3+} \), indicating oxidation.
Identify the oxidizing and reducing agents based on the changes in oxidation states. The substance that is reduced (gains electrons) is the oxidizing agent, and the substance that is oxidized (loses electrons) is the reducing agent.
Conclude that in this reaction, \( \text{Cr}_2\text{O}_7^{2-} \) is the oxidizing agent because it is reduced to \( \text{Cr}^{3+} \), and \( \text{Fe}^{2+} \) is the reducing agent because it is oxidized to \( \text{Fe}^{3+} \).
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