Question

Which of the following is the best reducing agent: \(\mathrm{F}_{2}, \mathrm{H}_{2}, \mathrm{Na}\) \(\mathrm{Na}^{+}, \mathrm{F}^{-} ?\) Explain. Order as many of these species as possible from the best to the worst oxidizing agent. Why can't you order all of them? From Table \(17-1\) choose the species that is the best oxidizing agent. Choose the best reducing agent. Explain.

Short answer

The best reducing agent among the given species is \(\mathrm{Na}\), as it has the lowest reduction potential of -2.71 V. The order of oxidizing agents based on reduction potentials is: F2 (best), H2, and Na, but Na+ and F- cannot be ordered as they cannot be reduced or oxidized, respectively. From Table 17-1, the overall best oxidizing agent is F2 with a reduction potential of +2.87 V, and the overall best reducing agent is Li with a reduction potential of -3.04 V.

Step-by-step solution

Recall the Reduction Potentials

Reduction potential is the tendency of a species to gain electrons and get reduced. A higher reduction potential means a higher tendency to get reduced, and a lower reduction potential means a higher tendency to lose electrons (get oxidized). Therefore, a good reducing agent will have lower reduction potential.

Compare given species' reduction potential

Let's use the standard reduction potentials from Table 17-1 for the given species: 1. F2: F2 + 2e- → 2F- : E° = +2.87V 2. H2: 2H+ + 2e- → H2: E° = 0 V (Standard Reference Electrode) 3. Na: Na+ + e- → Na : E° = -2.71V 4. Na+: Cannot be further reduced. 5. F-: Cannot be further oxidized.

Determine Best Reducing Agent

Since a good reducing agent will have a lower reduction potential, we can say that \(\mathrm{Na}\) is the best reducing agent among the given species.

Ranking Oxidizing Agents

To find the oxidizing agents, we need to go in the reverse order of reduction potential. Oxidizing agents will have a higher tendency to get reduced, so they will have a higher reduction potential. Based on the given reduction potentials, the order would be: 1. Best Oxidizing Agent: F2 2. H2 3. Na We cannot order Na+ and F- as oxidizing agents because they cannot be further reduced or further oxidized, respectively. So, these species are not considered as oxidizing agents.

Choose the Best Oxidizing and Reducing Agent from Table 17-1

Based on Table 17-1, Best Oxidizing Agent: F2, as it has the highest reduction potential, +2.87 V. Best Reducing Agent: Li, as it has the lowest reduction potential, -3.04 V. Thus, the best reducing agent among the given species is Na, and the overall best reducing agent based on Table 17-1 is Li. Similarly, the best oxidizing agent among the given species and overall is F2.

Key concepts

Reducing Agent

A reducing agent is a substance that donates electrons to another species in a chemical reaction. By doing this, it causes the other species to be reduced. For example, reducing agents are crucial in redox reactions where they lose electrons and become oxidized themselves. The strength of a reducing agent depends on its reduction potential.- Reducing agents with low reduction potentials tend to give up electrons easily.- In electrochemical terms, such agents are positioned lower on the reduction potential scale.From the given exercise, sodium (\(\mathrm{Na}\)) is an excellent example of a reducing agent, as it has a very low reduction potential of \(-2.71 \text{ V}\), allowing it to easily lose electrons. Thus, it readily oxidizes, making it a strong reducing agent.

Oxidizing Agent

An oxidizing agent is a substance that accepts electrons from another species. This electron acceptance causes the other species to be oxidized, which means the oxidizing agent itself is reduced.- Oxidizing agents are generally found at the higher end of the reduction potential scale.- They have a high affinity for electrons, making them potent in driving other substances to donate electrons and become oxidized.In the exercise, \(\mathrm{F}_{2}\) acts as the most powerful oxidizing agent because it has a high reduction potential of \(+2.87 \text{ V}\). This high value indicates a strong tendency to accept electrons and hence be reduced.

Electrochemistry

Electrochemistry is the branch of chemistry that deals with the study of chemical processes that cause electrons to move. This movement of electrons generates electricity, which is fundamental to numerous applications and systems. - Electrochemical reactions are crucial in batteries, electrolysis, and corrosion. - These reactions are characterized by a transfer of electrons between chemical species, involving reducing and oxidizing agents. Electrochemistry combines principles of physics and chemistry to understand processes like those described in the exercise. It allows us to predict the direction of redox reactions, based on the concepts of reduction potential. This field provides insights into why certain reactions occur, and it helps identify the best agents for these reactions, such as determining the best reducing or oxidizing agent from Tables like Table 17-1.

Standard Reduction Potentials

Standard reduction potentials are quantitative measures that help us understand the tendency of a chemical species to be reduced. They are often referenced against the standard hydrogen electrode, which is defined as having an electrode potential of \(0 \text{ V}\).- Each species has a unique reduction potential based on its ability to gain electrons.- Reduction potentials are essential to determine which species can act as good reducing or oxidizing agents.By looking at standard reduction potentials, we can rank species. Higher positive values indicate strong oxidizing agents (like \(\mathrm{F}_{2}\) in the exercise), while more negative values signify potent reducing agents (like \(\mathrm{Na}\)). This ranking is crucial for predicting reaction outcomes and for selecting materials for specific applications, like batteries.