Question

Use the following reactions to arrange the cations \(\mathrm{W}^{+}, \mathrm{X}^{+}, \mathrm{Y}^{+}\), and \(\mathrm{Z}^{+}\) in order of their increasing ability as oxidizing agents. $$ \begin{aligned} &\mathrm{W}^{+}+\mathrm{Z} \longrightarrow \text { no reaction } \\ &\mathrm{X}^{+}+\mathrm{W} \longrightarrow \text { no reaction } \\ &\mathrm{Y}^{+}+\mathrm{X} \longrightarrow \mathrm{X}^{+}+\mathrm{Y} \\ &\mathrm{Y}^{+}+\mathrm{Z} \longrightarrow \mathrm{Z}^{+}+\mathrm{Y} \end{aligned} $$

Short answer

Question: Based on the given reactions, arrange the cations W⁺, X⁺, Y⁺, and Z⁺ in terms of their increasing ability as oxidizing agents. Answer: W⁺ < X⁺ < Z⁺ < Y⁺.

Step-by-step solution

Understand the given reactions

We are given 4 reactions involving cations W⁺, X⁺, Y⁺, and Z⁺. Two of the reactions result in no reaction, which means the cations involved cannot cause a reduction reaction in each other. The other two reactions result in a reaction, indicating that the cation can cause a reduction reaction in the other cation.

Analyzing no reaction cases

First, let's analyze the two reactions where no reaction occurs: 1. W⁺ + Z → no reaction: This suggests that W⁺ is not a strong enough oxidizing agent to reduce Z, and Z⁺ is not a strong enough oxidizing agent to reduce W. 2. X⁺ + W → no reaction: This suggests that X⁺ is not a strong enough oxidizing agent to reduce W, and W⁺ is not a strong enough oxidizing agent to reduce X.

Analyzing reactions with reactions

Now, let's analyze the two reactions where a reaction occurs: 3. Y⁺ + X → X⁺ + Y: In this reaction, Y⁺ is able to reduce X, so Y⁺ is a stronger oxidizing agent than X⁺. 4. Y⁺ + Z → Z⁺ + Y: In this reaction, Y⁺ is able to reduce Z, so Y⁺ is a stronger oxidizing agent than Z⁺.

Arrange the cations in order of their increasing ability as oxidizing agents

Considering the information from the reactions, we can determine the following order: 1. W⁺ is not able to reduce X or Z, so it is the weakest oxidizing agent. 2. X⁺ is reduced by Y⁺ but does not reduce W or Z, so it is weaker than Y⁺ but stronger than W⁺. 3. Z⁺ is reduced by Y⁺ and does not reduce W, so it is weaker than Y⁺ but we cannot directly compare it with X⁺ and W⁺ from the given information. 4. Y⁺ is the strongest oxidizing agent among the given cations, as it reduces both X and Z. Thus, the order of increasing ability as oxidizing agents is: W⁺ < X⁺ < Z⁺ < Y⁺.

Key concepts

Redox Reactions

Redox reactions, short for reduction-oxidation reactions, are chemical processes where electrons are transferred between substances. These reactions are essential in understanding how elements interact in chemistry. In a redox reaction, one species undergoes oxidation, while another undergoes reduction. Oxidation involves the loss of electrons, whereas reduction involves the gain of electrons.
Oxidizing agents are species that accept electrons and, consequently, get reduced. In contrast, reducing agents donate electrons and get oxidized.

• Oxidation: Loss of electrons
• Reduction: Gain of electrons
• Oxidizing agent: Species that is reduced
• Reducing agent: Species that is oxidized

In the exercise, we need to categorize the cations based on their ability to act as oxidizing agents by examining how they interact in redox reactions.

Cation Reactivity

The reactivity of cations in redox reactions involves their potential to either donate or accept electrons. This determines their roles as either oxidizing or reducing agents.
In the given exercise, various cations (W⁺, X⁺, Y⁺, and Z⁺) demonstrate different reactivities in chemical reactions. By analyzing these reactions, the cations' efficiency in acting as oxidizing agents can be assessed.

• Reactivity indicates the ability to participate in electron transfer.
• More reactive cations can more readily accept electrons and act as stronger oxidizing agents.

For example, in the equation Y⁺ + X → X⁺ + Y, Y⁺ is more reactive than X⁺ as it can pull electrons from X, converting it into X⁺.

Oxidation-Reduction Chemistry

Oxidation-reduction chemistry is the fundamental study of how oxidation states of elements change through electron transfer. This branch of chemistry explains the energetic transformations in reactions that involve electron movement.
The exercise helps illustrate this concept by using specific reactions to show changes in oxidation states. Here, Y⁺ is observed to be the best oxidizing agent since it can reduce both X and Z. Below are the most important points:

• Each reaction reflects a shift in electron association.
• The ability to cause a change in another species' oxidation state indicates the strength of an oxidizing agent.

By comparing which cations can achieve these shifts, we arrange them from weakest to strongest oxidizing agents.