Which of the following species is the strongest reducing agent?

[TheJourney]

Which of the following species is the strongest reducing agent?

A. Cl2
B. Cu
C. Mg^2+
D. Zn

The answer is Zinc (D).
The explanation: "Reducing agents get oxidized so we need to reverse the reactions in Table 10.1. this eliminates choices A and C, because Cl2 and Mg^2+ cannot oxidize further. Between Zn and Cu, the more favorable oxidation (reverse reaction from Table 10.1) is found with zinc (0.76 > -0.34). Choice D is the best answer."

The Table they speak of sort of looks like this:

Half Reaction E (V)
Cl2 + 2 e --> 2 Cl^- 1.36
Cu^2+ + 2e --> Cu 0.34
Mg^2+ + 2e --> Mg -2.37
Zn^2+ + 2e --> Zn -0.76

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[BrawnsNBrain]

I would agree with D unless I'm missing something. What's the part that you don't understand?

 

[TheJourney]

I would agree with D unless I'm missing something. What's the part that you don't understand?

I'm kind of lost on how they were able to eliminate choices A and C

 

[BrawnsNBrain]

http://forums.studentdoctor.net/threads/which-is-the-strongest-reducing-agent-help.945434/

 

[benjaminl1nus]

You can eliminate A & C by this -

Cl2 is very electronegative. To be a reducing agent the species must have electrons that it's willing to surrender. something electron greedy like Cl2 will not surrender electrons easily.

Mg2+ is a species with a noble gas electron configuration. It's very stable as it is, and will neither prefer to give up electrons nor donate electrons.

Rule of thumb - the best reducing agent is the species with the lowest (or most negative) reduction potential.