Question

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

Short answer

Since metal A is a better reducing agent than metal B, it has a higher tendency to get oxidized and lose electrons, forming A+. Therefore, the cation A+ should have a higher reduction potential than B+, indicating that A+ is a better oxidizing agent than B+.

Step-by-step solution

Understand Reduction Potential

To analyze the relationship between A and B, we need to understand the concept of Reduction Potential. Reduction potential, or redox potential, is a measure of the tendency of a chemical species to undergo a reduction reaction. Reduction is the gain of electrons by an atom or ion. In a redox reaction, one species is reduced while the other is oxidized. A better reducing agent can donate electrons more easily than another reducing agent. Thus, a better reducing agent has a higher tendency to get oxidized (lose electrons).

Compare Metal A and Metal B

Since Metal A is a better reducing agent, it has a higher tendency to get oxidized than Metal B. When Metal A gets oxidized, it loses electrons to form A+ cation. On the other hand, when Metal B gets oxidized, it loses electrons to form B+ cation.

Relationship between A+ and B+

Since Metal A has a higher tendency to get oxidized compared to Metal B, its cation A+ should have a higher reduction potential than B+ cation. A higher reduction potential indicates that A+ can easily accept electrons and get reduced to Metal A. So, we can conclude that with respect to reduction potential, A+ should have a higher reduction potential than B+. This means that A+ is a better oxidizing agent than B+.

Key concepts

Reduction Potential

Reduction potential, often symbolized as E₀, reflects a substance's affinity for electrons, essentially telling us how likely it is to be reduced. You can think of it as a measure of the 'desire' of an atom or ion to gain electrons in an oxidation-reduction reaction. The higher the reduction potential, the greater its ability to gain electrons and be reduced.

Here's a useful tip: Think of reduction potential like a score in a game – the higher the score, the better potential a player (or ion) has to win (or be reduced). In essence, if Metal A is a better reducing agent than Metal B, it means that Metal A's ions, A+, have a higher score or reduction potential, meaning they are more likely to pick up electrons and revert back to uncharged Metal A.

Oxidation-Reduction Reaction

An oxidation-reduction reaction, commonly known as a redox reaction, involves the transfer of electrons from one substance to another. Remember that oxidation means losing electrons while reduction means gaining electrons. In every redox reaction, there is a transfer of electrons from the reducing agent to the oxidizing agent.

For students, a simple analogy might be helpful: Consider a redox reaction as a dance between two partners, the reducing agent and the oxidizing agent. The reducing agent, like a generous dance partner, gives away its electrons, while the oxidizing agent gladly accepts them. In the context of our exercise, Metal A, being the better reducing agent, is like the most skilled dancer, adept at giving away electrons to other species in the reaction.

Electron Transfer

Electron transfer is the crux of redox reactions. It's the actual 'transaction' where the reducing agent gives up electrons while the oxidizing agent accepts them. It's important to realize that this is an all-or-nothing exchange; an electron cannot be partially transferred.

Imagine electrons as currency in an economy. In a redox 'transaction,' electrons are 'spent' by the reducing agent (like money paid out) and 'earned' by the oxidizing agent (like money received). For a student, envisioning this as a simple exchange of coins can demystify electron transfer. Our Metal A, being a better reducing agent, 'spends' its electrons more readily than Metal B which is less 'generous'.

Redox Potential

Redox potential, also known as oxidation-reduction potential or ORP, is a numerical way of describing a substance's ability to either gain or lose electrons, combining both aspects of reduction and oxidation. Measured in volts, redox potential provides a scale, with higher positive values indicating stronger oxidizing agents and lower negative values indicating stronger reducing agents.

Students might find it easier to think of redox potential as a leaderboard. Those with higher positive values are 'winning' in terms of being better oxidizers (they accept electrons), while those with more negative values are 'at the top' for being good reducers (they donate electrons). Metal A's high tendency to lose electrons correlates with a higher ORP when it's in the form of an ion, A+, suggesting it can be easily reduced back.