Oxidation/Reduction

[Dave12314]

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Can someone help clarify this.. I thought I understood it but apparently not

Which of the following is the STRONGEST reducing agent?

The answer is Zn

So to my understanding the strongest reducing agent is the one most easily oxidized. So since the half rxns of both Mg2+ and Zn2+ have a negative emf then we flip it. So is Zn the answer because it requires the least amount of energy to be oxidized?

Also in the answer explanation it says that Mg2+ is an oxidizing agent which confused me even more because I thought since its easily oxidized that its a reducing agent??

 

[MedPR]

Can someone help clarify this.. I thought I understood it but apparently not

Which of the following is the STRONGEST reducing agent?

The answer is Zn

So to my understanding the strongest reducing agent is the one most easily oxidized. So since the half rxns of both Mg2+ and Zn2+ have a negative emf then we flip it. So is Zn the answer because it requires the least amount of energy to be oxidized?

Also in the answer explanation it says that Mg2+ is an oxidizing agent which confused me even more because I thought since its easily oxidized that its a reducing agent??

It appears that Mg is the strongest reducing agent since the value is the most negative.. I don't know the answer to why Zn is a stronger reducing agent, however, you can clearly see in that chart that Mg2+ gains 2 electrons (is reduced), thus making it an oxidizing agent.

 

[Dave12314]

It appears that Mg is the strongest reducing agent since the value is the most negative.. I don't know the answer to why Zn is a stronger reducing agent, however, you can clearly see in that chart that Mg2+ gains 2 electrons (is reduced), thus making it an oxidizing agent.

That's what I had thought to. Maybe its Zn because if you flip the equations around.. Zn requires the least amount of energy to be oxidized.. making it the strongest reducing agent?

 

[MedPR]

That's what I had thought to. Maybe its Zn because if you flip the equations around.. Zn requires the least amount of energy to be oxidized.. making it the strongest reducing agent?

Idk, are you sure the answer is correct?

If Mg donates 2 electrons, its electron configuration becomes [Ne] and if Zn donates 2 electrons, it becomes [Ni]. Mg should be the better reducing agent..

 

[Ssina]

I've seen this question in one of the FLs, the answer actually doesn't have Mg(s), it has Mg+ (or 2+), which will not have as positive of oxidation potential as Zn.... so Zn is the best reducing agent.

also since the oxidation potential is positive (and assuming we use something that has a positive reduction potential also) we will get energy out, instead of using less energy as you mentioned (from deltaG= -nFEcell)

 

[Dave12314]

Not sure if its correct but heres the answer reasoning it gave:

The best reducing agent is the compound that is most favorably oxidized. According to the table, Mg2+(aq) is an oxidizing agent, because it has no electrons to lose and can gain two electrons to form the neutral metal. This eliminates choice B. According to the chart, it is unfavorable to oxidize Cl-(aq) or MnO(s) (both have negative voltages for oxidation), so choices A and C are eliminated. The oxidation potential for Zn(s) is +0.76 V, making it the strongest reducing agent of the four answer choices.

Still doesn't make sense though.

 

[Ssina]

o ok so they actually had Mg 2+
yeah so being a reducing agent, requires to give up an electron (reduce something else) and become oxidized yourself... the table lists the oxidation potential for Mg solid (if you flip the reduction potential from the table in the OP), not Mg2+ that the answer choice B has... so you can't pick that one

 

[MedPR]

Not sure if its correct but heres the answer reasoning it gave:

The best reducing agent is the compound that is most favorably oxidized. According to the table, Mg2+(aq) is an oxidizing agent, because it has no electrons to lose and can gain two electrons to form the neutral metal. This eliminates choice B. According to the chart, it is unfavorable to oxidize Cl-(aq) or MnO(s) (both have negative voltages for oxidation), so choices A and C are eliminated. The oxidation potential for Zn(s) is +0.76 V, making it the strongest reducing agent of the four answer choices.

Still doesn't make sense though.

What are the answer choices

Zn is a stronger reducing agent than Mg2+
Mg is a stronger reducing agent than Zn.

If the answer opposes that, then idk.

 

[Dave12314]

What are the answer choices

A. MnO (s)
B. Mg2+ (aq)
C. Cl- (aq)
D. Zn (s)

 

[Dave12314]

o ok so they actually had Mg 2+
yeah so being a reducing agent, requires to give up an electron (reduce something else) and become oxidized yourself... the table lists the oxidation potential for Mg solid (if you flip the reduction potential from the table in the OP), not Mg2+ that the answer choice B has... so you can't pick that one

No they had Zn (option D) as the answer from the choices below:

A. MnO (s)
B. Mg2+ (aq)
C. Cl- (aq)
D. Zn (s)

 

[MedPR]

A. MnO (s)
B. Mg2+ (aq)
C. Cl- (aq)
D. Zn (s)

No they had Zn (option D) as the answer from the choices below:

A. MnO (s)
B. Mg2+ (aq)
C. Cl- (aq)
D. Zn (s)

There's your answer. Mg2+ is not a reducing agent. Reducing agents donate electrons in order to reduce something. Reduction is the gain of electrons, so reducing agents lose electrons. Mg2+ has no electrons to lose, but it readily gains 2 electrons.

In Mg2+ +2e- ---> Mg (or Mg ---> 2e- +Mg2+)

Mg = reducing agent = gets oxidized = loses electrons
Mg2+ = oxidizing agent = gets reduced = gains electrons

 

[Dave12314]

There's your answer. Mg2+ is not a reducing agent. Reducing agents donate electrons in order to reduce something. Reduction is the gain of electrons, so reducing agents lose electrons. Mg2+ has no electrons to lose, but it readily gains 2 electrons.

In Mg2+ +2e- ---> Mg (or Mg ---> 2e- +Mg2+)

Mg = reducing agent = gets oxidized = loses electrons
Mg2+ = oxidizing agent = gets reduced = gains electrons

Ok now I understood it thanks! Suppose it was Mg though, looking at the emf in the table given, its the one with the greatest emf that would correspond to the best reducing agent right?

 

[MedPR]

Ok now I understood it thanks! Suppose it was Mg though, looking at the emf in the table given, its the one with the greatest emf that would correspond to the best reducing agent right?

Yes, Mg is a better reducing agent than Zn.

They probably put Mg2+ in there to make sure you were paying attention.