Question

Using the tables, of standard electrode potentials, list the fol lowing ions in order of decreasing ability as oxidizing agents: \(\mathrm{Fe}^{3+}, \mathrm{F}_{2}, \mathrm{~Pb}^{2+}, \mathrm{I}_{2}, \mathrm{Sn}^{4+}, \mathrm{O}_{2}\)

Short answer

The ordered list of the given ions and molecules in decreasing ability as oxidizing agents, using standard electrode potentials, is: \(\mathrm{F}_{2} > \mathrm{Fe}^{3+} > \mathrm{I}_{2} > \mathrm{O}_{2} > \mathrm{Sn}^{4+} > \mathrm{Pb}^{2+}\)

Step-by-step solution

Find the standard electrode potentials

Consult the standard electrode potentials table and find the standard electrode potential (E°) for each given species. Typically, these values can be found in a table within a textbook or online. We find the following values: \(E_{\mathrm{Fe}^{3+}/\mathrm{Fe}^{2+}} = 0.77V\) \(E_{\mathrm{F}_{2}/\mathrm{F}^-} = 2.87V\) \(E_{\mathrm{Pb}^{2+}/\mathrm{Pb}} = -0.13V\) \(E_{\mathrm{I}_2/\mathrm{I}^-} = 0.54V\) \(E_{\mathrm{Sn}^{4+}/\mathrm{Sn}} = 0.15V\) \(E_{\mathrm{O}_2/\mathrm{O}^{2-}} = 0.40V\)

Order the species

Now that we have the standard electrode potentials for each species, we can order them in terms of decreasing ability as oxidizing agents. We should start with the highest standard electrode potential and proceed to the lowest. Thus, the order should be: \(\mathrm{F}_{2} \to \mathrm{Fe}^{3+} \to \mathrm{I}_{2} \to \mathrm{O}_{2} \to \mathrm{Sn}^{4+} \to \mathrm{Pb}^{2+}\)

Present the final ordered list

The final ordered list, in decreasing ability as oxidizing agents, is: \(\mathrm{F}_{2} > \mathrm{Fe}^{3+} > \mathrm{I}_{2} > \mathrm{O}_{2} > \mathrm{Sn}^{4+} > \mathrm{Pb}^{2+}\)

Key concepts

Oxidizing Agents

When we talk about oxidizing agents, we're discussing substances that have the ability to accept electrons during chemical reactions. They "oxidize" other substances by taking electrons away from them. This might seem counterintuitive at first because they're getting reduced themselves.
A powerful oxidizing agent will have a strong tendency to grab electrons. One way to figure out the strength of an oxidizing agent is by looking at its reduction potential.
If a species has a high reduction potential, it means it's a strong oxidizing agent as it more readily accepts electrons. In the exercise, we ranked these agents based on their standard electrode potential, because that's a good indicator of their oxidizing power.
Fluorine, with the highest standard electrode potential in the list, ends up as the strongest oxidizing agent in the exercise, while lead(II) ion with the lowest potential ranks weakest.

Electrochemistry

Electrochemistry is the branch of chemistry that deals with the relationship between electricity and chemical changes. When chemical reactions involve the transfer of electrons, that's what electrochemistry is all about.
This field is crucial because it helps us understand and harness chemical reactions to generate electricity (like in batteries) or use electricity to drive chemical reactions (like in electrolysis).
Standard electrode potentials are significant in electrochemistry since they allow us to predict the direction and feasibility of redox reactions.

• They offer insights into the energy changes associated with electron transfer.
• They help in constructing electrochemical cells and predicting their voltage.

Understanding these concepts allows for advancements in technologies like fuel cells and corrosion prevention.

Reduction Potential

Reduction potential is a measure of the tendency of a chemical species to gain electrons and be reduced. It is usually expressed in volts (V).
The higher the reduction potential, the greater the species' ability to acquire electrons, indicating it is more favorable for the species to undergo reduction.
This concept is essential in ranking oxidizing agents. In standard conditions (which is what "standard electrode potentials" refer to) each electrode potential is measured against a standard hydrogen electrode.

• A positive reduction potential suggests a strong oxidizing agent.
• A negative reduction potential indicates a weaker oxidizing agent or even a reducing agent in some cases.

It's handy for chemists to quickly determine which species will act as oxidizing or reducing agents in a reaction.

Redox Reactions

Redox reactions are chemical processes that involve the transfer of electrons between two substances. They can be broken down into two half-reactions: oxidation and reduction.

- **Oxidation** is when a substance loses electrons, increasing its oxidation state. - **Reduction** involves a substance gaining electrons, decreasing its oxidation state.
Electrochemistry revolves a lot around redox reactions, as the movement of electrons in these reactions is what generates electrical energy in cells or requires it in other processes.
Balance in redox reactions involves ensuring that the number of electrons lost equals the number gained. Understanding how to separate these reactions into two halves helps in balancing complex equations and predicting the products of reactions.
To determine which substance gets oxidized or reduced, looking at standard electrode potentials guides us since the species with the higher potential gets reduced.