GS-2 Physical Sciences Question 21

[jgeng03]

Wouldn't we want a high E value for Zn so that it would more easily give up its elections and combine with OH and therefore protect Fe?

[admin]

Yes, you are correct. But you chose the incorrect answer.

You want the Eo value for the loss of electrons by Zn to be greater than the Eo value for the loss of electrons by Fe. But that would be written as:

Eo(Zn/Zn2+) > Eo(Fe/Fe2+)

Which is the same as answer choice D which is written as a reduction:

Eo(Zn2+/Zn) < Eo(Fe2+/Fe)

[pinoalejan6739]

I understand the explanation to this question, if zinc oxidizes better then iron than more cations will be ready to react with hydroxide. What I don't understand is why it isn't answer A. If zinc doesn't form a strong bond with hydroxide who cares if it is ionized or not it is still not going to protect iron. The lower the Ksp of zinc the more it wants to form a bond with hydroxide and protect iron from undergoing that reaction.

[hua8986059]

Didn't know what these notations mean, but now I do. Concepts were not intense the way the question was asked is intense.

[btdumford5156]

Thank you for this question, and intuitively I got it correct but conceptually I feel like im not connecting with the actuallity of the question. What is the concept being tested in this question; can you please summarize the concept in a breif explaination?

[mohsinalam5969]

Galvanization (or galvanisation) is the process of applying a protective metallic coating to an underlying piece of metal, in order to prevent rusting.
the copper and the zinc are in contact, either directly or by means of a wire.
The electrode reactions are:
at the zinc electrode:
Zn(s) → Zn2+(aq) + 2e–
followed by complexing of the zinc ions as Zn(OH)4
2–(aq)
at the copper electrode:
Zn(OH)4
2–(aq) + 2e– → Zn(s) + 4OH–(aq)
A similar zinc plating process is used industrially but with cyanide ions rather
than hydroxide ions as the complexing agent.
Brass is an alloy of copper containing between 18 % and 40 % of zinc.

More negative the Eo value, the greater the tendency for the equilibrium to shift to the left, that is, toward the production of cations. In order to minimize the reaction with Fe (rusting) and maximize the reaction with Zn (galvanizing), we want the following: since the cation of Zn is supposed to react more readily with the hydroxide ions than with iron, it would be facilitated if it ionized more readily than the iron, that is, if its standard reduction potential was more negative than that of iron.