Reduction

[pm1]

I've been staring at a question for a while now but I can't seem to get it right.. If someone could please help me out...

So here is what the passage says about reduction. (ps, the passage is about processes through which you can decontaminate water).

In reverse osmosis, contaminated water is pumped into a vessel that often contains a substance that reduces the contaminants. Toxins that easily gain electrons have higher reduction potentials than those that do not. The water is then mechanically pushed across a thin semi-permeable membrane that does not allow contaminants to pass through.

Then the question:

2. Which one of the following ions is expected to be most resistant to a reducing agent during reverse osmosis?
A. Ni2+
B. Cu2+
C. Zn2+
D. Ga2+


Answer : B

So what I got from all this is that, according to the passage, toxins that have a higher electron affinity will have a higher reduction potential.
My background knowledge tells me that electron affinity increases as we go from left to right on a period. The ions with greater resistance to a reducing agent are the ones that are less likely to be reduced - hence smaller electron affinity. Thus, shouldn't the answer be Ni2+?
I'm confused..

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[411309]

I would think copper would want to get reduced as opposed Ni. So im confused as well.

 

[typicalindian]

I would think copper would want to get reduced as opposed Ni. So im confused as well.

same...Isn't Cu2+ 3d9? so it would love to have that extra electron wouldn't it?

 

[gettheleadout]

Reduction potentials from the interwebz:

Cu2+ + 2e- -> Cu = +0.34
Ni2+ + 2e- -> Ni = -0.25
Zn2+ + 2e- -> Zn = -0.76
Ga2+ + 2e- -> Ga = -0.45

So wouldn't Cu2+ actually be the least resistant to a reducing agent?

 

[pm1]

yea.. Idk. I'm glad I'm not the only one confused though... :/
they don't give an explanation, just the correct answer. I guess at least we are all the same page.

 

[MedPR]

The fact that a simple misread (and mistype) of the question could lead you away from Cu2+ makes me think that might be what happened here. Cu2+ is obviously the most readily reduced of those 4..

 

[pfaction]

Reduction potentials from the interwebz:

Cu2+ + 2e- -> Cu = +0.34
Ni2+ + 2e- -> Ni = -0.25
Zn2+ + 2e- -> Zn = -0.76
Ga2+ + 2e- -> Ga = -0.45

So wouldn't Cu2+ actually be the least resistant to a reducing agent?

If the #'s are correct, it should be Zn that's the most resistant to a reducing agent.

 

[MedPR]

If the #'s are correct, it should be Zn that's the most resistant to a reducing agent.

Indeed. Zn2+ the most, Cu2+ the least.

 

[gettheleadout]

OP, where is this question from?

 

[MedPR]

Maybe this is based on some physio passage that tells you Cu2+ is not readily reduced.. Either some outside information (passage) explains this as an exception, or there is an error.

 

[gettheleadout]

Maybe this is based on some physio passage that tells you Cu2+ is not readily reduced.. Either some outside information (passage) explains this as an exception, or there is an error.

Wouldn't that make the question really easy? Just saying.

 

[MedPR]

Wouldn't that make the question really easy? Just saying.

Only if you noticed that the passage mentioned it. Maybe it's just me, but I've noticed quite a few "did you read the passage?" types of questions on the AAMC FLs. Sometimes they are questions that you can figure out based on background knowledge, but other times they are questions that, if you use background knowledge, you will get them wrong because the passage stated otherwise.

 

[pm1]

OP, where is this question from?

from TPRH class compendium. I copied straight from a PDF file thus no mistypes...

 

[gettheleadout]

Only if you noticed that the passage mentioned it. Maybe it's just me, but I've noticed quite a few "did you read the passage?" types of questions on the AAMC FLs. Sometimes they are questions that you can figure out based on background knowledge, but other times they are questions that, if you use background knowledge, you will get them wrong because the passage stated otherwise.

Interesting, good to know.

from TPRH class compendium. I copied straight from a PDF file thus no mistypes...

PDF, eh?

 

[pm1]

Interesting, good to know.

PDF, eh?

yep I bought from some guy.. here on SDN actually. But then only after paying $$$ I saw that there were no explanations only the answer.

 

[MedPR]

Interesting, good to know.

Very few of the latter, but many of the former. For instance the passage may tell you stuff like "Sally had a relaxing and stress free skiing vacation with her family."

Then a question is:

"Sally experienced increased heart rate and respiration rate during her family vacation. What is the likely cause?"

A. Sally doesn't like her family and her negative feelings towards them excited her sympathetic nervous system.
B. Sally was hypoxic due to the low atmospheric PO2.

So if you hadn't read the passage, you might be stuck between A and B since both are valid reasons for her conditions. But if you saw that she went skiing, you probably would've known the answer to the question without even reading the answers and you (I) immediately look for hypoxia or something related to the high altitude and move on.

 

[MedPR]

yep I bought from some guy.. here on SDN actually. But then only after paying $$$ I saw that there were no explanations only the answer.

The guy probably downloaded the PDF from the internet.

I may or may not have found copies of the 2009 TBR books after I had already purchased the 2011 books. These 2009 copies, which I may or may not have downloaded, may or may not have been very helpful while I was at work and could not have a book but could read PDFs that I may or may not have downloaded.

 

[gettheleadout]

yep I bought from some guy.. here on SDN actually. But then only after paying $$$ I saw that there were no explanations only the answer.

Yeah, that's illegal. In the future you should report users who solicit digital materials.

 

[pm1]

Yeah, that's illegal. In the future you should report users who solicit digital materials.

okay thanks for letting me know. I think I wasted some money when I thought I was getting a good deal and supporting illegal stuff.. but anyways, thanks for letting me know. I thought that since it was sold through sdn it was okay.

 

[MedPR]

okay thanks for letting me know. I think I wasted some money when I thought I was getting a good deal and supporting illegal stuff.. but anyways, thanks for letting me know. I thought that since it was sold through sdn it was okay.

Nothing bought over the internet is ever ok unless it's an official type of thing. I tried to buy used TBR books here and everyone I talked to tried to get me to gift the money to them so that they didn't have to pay paypal fees. Straight up scam.

 

[typicalindian]

Nothing bought over the internet is ever ok unless it's an official type of thing. I tried to buy used TBR books here and everyone I talked to tried to get me to gift the money to them so that they didn't have to pay paypal fees. Straight up scam.

you can still re-claim your money even if it's sent as a gift. just sayin

 

[MedPR]

you can still re-claim your money even if it's sent as a gift. just sayin

I thought I read on paypal that you can't reclaim it. That giving it as a gift is as good as handing a stranger money..?

 

[411309]

I just thought of the answer...If the induced polarity caused by the attachment of the toxins adds more the effective nuclear charge, this causes an increase in the radi of the electron making it having a weaker interaction to the positive charge of the nucleus making it resistant reduction because the overall net charge of the atom becomes highly negative, therefore pushing extra electrons away.





















Im jk

 

[typicalindian]

I thought I read on paypal that you can't reclaim it. That giving it as a gift is as good as handing a stranger money..?

Nope I can guarantee you can get it back in many situations.

 

[MedPR]

Nope I can guarantee you can get it back in many situations.

Oh, well that's good to know for future I guess. The guy wanted like $40 less than the brand new books cost + shipping, so I don't regret getting the new ones.

 

[soupcoop]

The configuration of Ga2+ is 4s1 3d10. Since the 3d is further from the nucleus, it essentially has a full valence shell. It is the least reactive. Thats my understanding and the way the Princeton instructor explained it.

 

[Dasypus]

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