TBR, Gchem, Atomic Theory, Passage 5 # 34

[Sammy1024]

34. If the pore of the membrane used in the experiment is associated with Table 1 were to distinguish by both size and charge, the SLOWEST rate would occur with which cation?

A. Li+
B. K+
C. Mg2+
D. Ca2+

The answer is D, but I picked B. Looking at the data in table 1, K+ clearly has the slowest rate so why would it be D? The answer says it is D because a larger charge would have a harder time getting through, BUT then wouldn't Ca2+ have a slower rate in the table??

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[dudewheresmymd]

I don't think this is a very good question. It's misleading. I too would have picked B as it's larger than Ca2+. might be a typo?

 

[DrknoSDN]

Not a typo, the trends in table one correlate to atomic size only. Smallest to largest Li+, Mg2+, Na+, Ca2+, K+.
Charge variation just causes K+ to be more permeable than Ca2+.

But you're right. This is not the greatest question.

 

[Sammy1024]

Thank you! :]