Four alkali metals A, B, C and D are having respectively standard electrode potentials as –3.05, –1.66, –0.40, and 0.80 V. Which one will be most reducing?

A

The correct answer is option 1. A.

To explain why the metal with the most negative standard electrode potential is the most reducing, let's delve into some key concepts:

Electrode Potential:

Standard Electrode Potential (\( E^\circ \)) measures how easily a species gains or loses electrons in a redox reaction. For a metal, the standard electrode potential indicates its tendency to lose electrons (oxidation) and form positive ions.

Reduction Potential:

A more negative standard electrode potential means that the metal is more likely to be oxidized (lose electrons) compared to metals with less negative or positive electrode potentials.

The Role of Reducing Agents

Reducing Agent:

A reducing agent is a substance that donates electrons to another species and gets oxidized in the process. The stronger the reducing agent, the more readily it loses electrons.

Reducing Strength:

Metals with more negative electrode potentials have a greater tendency to lose electrons. Therefore, they are stronger reducing agents because they donate electrons more easily.

Given Electrode Potentials

Here are the given standard electrode potentials for the metals:

Metal A: –3.05 V

Metal B: –1.66 V

Metal C: –0.40 V

Metal D: 0.80 V

Comparison

1. Metal A (–3.05 V):

This metal has the most negative electrode potential. It is the most prone to losing electrons (being oxidized) among the four metals. As a result, Metal A is the strongest reducing agent because it readily donates electrons.

2. Metal B (–1.66 V):

This metal has a less negative electrode potential compared to Metal A. It is a weaker reducing agent than Metal A but still a reducing agent.

3. Metal C (–0.40 V):

This metal has an even less negative electrode potential. It is a weaker reducing agent than both Metals A and B.

4. Metal D (0.80 V):

This metal has a positive electrode potential. It is the least likely to lose electrons and thus the weakest reducing agent among the four metals.

Conclusion

Metals with more negative electrode potentials are more effective at donating electrons (reducing agents) because they are more easily oxidized. Metal A, with the most negative electrode potential of –3.05 V, is the most reducing among the four metals.  Thus, the metal with the most negative standard electrode potential is the strongest reducing agent.