Problem 14.25


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Sydney Wu 2M
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Joined: Fri Jul 22, 2016 3:00 am

Problem 14.25

Postby Sydney Wu 2M » Sun Feb 05, 2017 4:37 pm

"Arrange the following metals in order of increasing strength as reducing agents for species in aqueous solution:
(a) Cu, Zn, Cr, Fe (b) . . . "

When looking up the standard reduction potentials in Appendix 2B, there are multiple values for some of the metals (i.e. Cu has E* values for Cu+ + e- --> Cu, Cu2+ + 2e- --> Cu, and Cu2+ + e- --> Cu+). Which value should we use to compare the metals?

Chem_Mod
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Re: Problem 14.25

Postby Chem_Mod » Sun Feb 05, 2017 9:12 pm

You should use a reaction that is seen in all of the species listed. For part a), Copper, Chromium and Iron do present different reactions and consequently different reduction potentials; however, there is only one reduction potential listed for Zinc. Thus, you should choose reactions similar in structure to compare the four with, like , for this specific question, it is where n is a charge number.

Madeline_Foo_3J
Posts: 26
Joined: Wed Sep 21, 2016 3:00 pm

Re: Problem 14.25

Postby Madeline_Foo_3J » Wed Feb 08, 2017 3:02 pm

Is the reason why Cr is the strongest reducing agent because you have to flip the sign of its standard potential to make it a reducing agent?

Absolute Zero 1O
Posts: 14
Joined: Wed Sep 21, 2016 2:56 pm

Re: Problem 14.25

Postby Absolute Zero 1O » Thu Feb 09, 2017 6:43 am

From Chemical Principles 6th edition, Problem 14.25 part B, we must order from least to greatest reducing agent for Li, Na, K, Mg. My issue is that Lithium can only lose one electron but it shows that Mg can lose only two electrons in the appendix. So what do we do in this case?


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