Does anyone know why Mg2+ can't be further oxidized?

[deleted647690]

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This is in reference to a question in BR, which asks "Which of the following species is the strongest reducing agent?
A. Cl2
B. Cu
C. Mg2+
D. Zn"

The answer is Zn. I would have thought Mg2+, because if it loses another electron, it reaches a stable form, so I would think oxidation is preferred. Plus, according to the table they give, the oxidation potential for Mg is 2.37, which is greater than that given for Zn. Their reasoning for why it wasn't Mg2+ was that it cannot be further oxidized.


I guess the reaction given in the table would give you the oxidation potential for Mg and not Mg2+, so we don't really know the oxidation potential for Mg2+. However, I still don't see how the noble gas stability reasoning doesn't work

 

[theonlytycrane]

Mg2+ is already in noble gas configuration!

 

[deleted647690]

Mg2+ is already in noble gas configuration!

Oh snap my bad. I counted the electrons incorrectly......

 

[theonlytycrane]

Use the periodic table if you're ever unsure. Check the group (column) of Mg and go back by 2 atomic numbers to Ne.

 

[aldol16]

Even if you're not a chemist, it's a good idea to have an idea of what common ions are, i.e. Mg2+, Zn2+, Cu+, Cu2+, Na+, K+, Cl-, etc.

 

[ImDiene0412]

If the forward half-reaction is mg2+ + 2e- --> Mg , why is the reverse rxn not Mg - 2e- --> Mg2+ ? I understand that Mg2+ is already in noble gas configuration, but thought the reverse reaction and corresponding value would have referred to Mg?

 

[ImDiene0412]

If the forward half-reaction is mg2+ + 2e- --> Mg , why is the reverse rxn not Mg - 2e- --> Mg2+ ? I understand that Mg2+ is already in noble gas configuration, but thought the reverse reaction and corresponding value would have referred to Mg?

Never mind, answered my own question- just needed to read more carefully.

 

[LoveBeingHuman:)]

Why wouldn't it be Cu?

 

[aldol16]

Why wouldnt it be Cu?

Take a look at redox table: http://www.chemeddl.org/services/moodle/media/QBank/GenChem/Tables/EStandardTable.htm

They were given a table that wasn't copied here.