Question

You are told that metal \(\mathrm{A}\) is a better reducing agent than metal B. What, if anything, can be said about \(\mathrm{A}^{+}\) and \(\mathrm{B}^{+}\) ? Explain.

Short answer

In conclusion, since metal A is a better reducing agent than metal B, this implies that A has a more negative standard reduction potential than B. Therefore, A⁺ will have a less positive (or more negative) standard reduction potential than B⁺. Consequently, B⁺ is a stronger oxidizing agent than A⁺, meaning it will tend to gain electrons more readily than A⁺.

Step-by-step solution

Understanding reducing agents

A reducing agent is a substance that donates electrons in a redox reaction, thereby causing the other substance to be reduced. In our case, metal A and metal B act as reducing agents.

Relating reducing agents to reduction potentials

The standard reduction potential is a measure of the tendency of a chemical species to be reduced. A more negative standard reduction potential indicates that a species is more likely to donate electrons (thus, it is a better reducing agent). Conversely, a more positive standard reduction potential indicates that a species is less likely to donate electrons (thus, it is a less effective reducing agent).

Comparing the reduction potentials of A⁺ and B⁺

Since metal A is a better reducing agent than metal B, we can deduce that A has a more negative standard reduction potential than B. This means that A is more likely to donate electrons than B. Now, we need to analyze the relationship between the standard reduction potentials of the metal ions A⁺ and B⁺.

Relationship between metal ions and their standard reduction potentials

When a metal is oxidized to its ionic form (A → A⁺ + e⁻ or B → B⁺ + e⁻), its standard reduction potential becomes more positive. Therefore, in this case, the standard reduction potentials of A⁺ and B⁺ are the reverse of their metallic forms (A and B).

Comparing A⁺ and B⁺ based on their reducing nature

Since metal A is a better reducing agent and has a more negative standard reduction potential than metal B, it means that A⁺ will have a less positive (or more negative) standard reduction potential than B⁺. Therefore, we can conclude that B⁺ is a stronger oxidizing agent compared to A⁺. A stronger oxidizing agent will have a greater tendency to be reduced, i.e., it will tend to gain electrons more readily than a weaker oxidizing agent. In conclusion, since metal A is a better reducing agent than metal B, B⁺ is a stronger oxidizing agent than A⁺.

Key concepts

Standard Reduction Potential

The standard reduction potential is a pivotal concept in understanding redox reactions and the behavior of reducing and oxidizing agents. It serves as a measure of the willingness of a substance to gain electrons, thereby undergoing reduction. The potential is usually measured in volts under standard conditions, which include a concentration of 1 M, a pressure of 1 atm, and a temperature of 25°C.

**Understanding the Values:**

• A more negative standard reduction potential indicates a greater tendency for the species to act as a reducing agent. This means it is more inclined to lose electrons.
• A more positive standard reduction potential suggests that the species has a higher tendency to gain electrons, making it a stronger oxidizing agent.

In the original exercise, since metal A is described as a better reducing agent than metal B, A must have a more negative standard reduction potential than B. In terms of their ionic forms, the situation reverses, leading A⁺ to have a more positive potential than B⁺, thereby indicating A⁺ as a weaker oxidizing agent compared to B⁺.

Oxidizing Agents

Oxidizing agents play a crucial role in redox reactions, where they gain electrons and are reduced themselves. By accepting electrons from another substance, they facilitate the oxidation of that substance. Because of this role, they are essential to countless chemical processes.

**Characteristics of Strong Oxidizing Agents:**

• They have a high affinity for electrons.
• Typically, they possess a positive standard reduction potential.
• Their ability to oxidize other substances makes them very reactive.

According to the solution given for the exercise, B⁺ is a stronger oxidizing agent compared to A⁺. This is because B⁺ has a greater tendency to gain electrons, as implied by its potentially more positive standard reduction potential. It's this ability that makes B⁺ efficient at oxidizing substances, while A⁺ does not quite match up.

Redox Reactions

Redox reactions, short for reduction-oxidation reactions, represent a fundamental type of chemical reaction involving the transfer of electrons between two substances. In these reactions, one reactant undergoes oxidation (loses electrons), while the other undergoes reduction (gains electrons).

**Components of Redox Reactions:**

• **Reducing Agent:** Donates electrons and becomes oxidized. In the context of the exercise, metal A is the reducing agent since it donates electrons more readily compared to metal B.
• **Oxidizing Agent:** Accepts electrons and becomes reduced. Here, B⁺ acts as the oxidizing agent because it gains electrons more easily than A⁺.

Balancing redox reactions is crucial to ensure that the number of electrons lost in oxidation matches the number gained in reduction. Understanding the interplay between reducing and oxidizing agents via their standard reduction potentials can greatly clarify the outcomes and paths of these reactions.