Arrange the following substances in order of increasing strength as an oxidizing agent, and account for the trend. (a) Cr2+ (b) Cr3+ (c) Cr2O72-

Name: Chemistry
Author: McMurry
ISBN: 9781292336145

검증된 단계별 안내

Step 1: Understand the concept of an oxidizing agent. An oxidizing agent is a substance that gains electrons in a chemical reaction and is reduced in the process. The strength of an oxidizing agent is determined by its ability to accept electrons.

Step 2: Consider the oxidation states of chromium in each species. For Cr^{2+}, the oxidation state is +2; for Cr^{3+}, it is +3; and for Cr_2O_7^{2-}, it is +6.

Step 3: Recognize that a higher oxidation state generally indicates a stronger oxidizing agent because it has a greater tendency to gain electrons to be reduced to a lower oxidation state.

Step 4: Compare the oxidation states: Cr_2O_7^{2-} has the highest oxidation state (+6), followed by Cr^{3+} (+3), and then Cr^{2+} (+2). Therefore, Cr_2O_7^{2-} is expected to be the strongest oxidizing agent.

Step 5: Arrange the substances in order of increasing strength as an oxidizing agent: Cr^{2+} < Cr^{3+} < Cr_2O_7^{2-}. This order is based on their ability to gain electrons and be reduced.

주요 개념

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Oxidizing Agents

An oxidizing agent is a substance that gains electrons in a chemical reaction, causing another substance to be oxidized. The strength of an oxidizing agent is determined by its ability to accept electrons; stronger oxidizers have a greater tendency to undergo reduction. Understanding the oxidation states and the electron configurations of the substances involved is crucial for determining their oxidizing strength.

Oxidation States

Oxidation states (or oxidation numbers) indicate the degree of oxidation of an atom in a compound. For example, in Cr2+, chromium has an oxidation state of +2, while in Cr3+, it is +3. The higher the oxidation state, the stronger the oxidizing ability, as the species is more likely to gain electrons to revert to a lower oxidation state.

Chromate Ion (Cr2O72-)

The chromate ion (Cr2O72-) is a well-known oxidizing agent in aqueous solutions. It contains chromium in a +6 oxidation state, which is significantly higher than that in Cr2+ and Cr3+. This high oxidation state allows Cr2O72- to readily accept electrons, making it a stronger oxidizing agent compared to Cr2+ and Cr3+.