NS FL 10 CP Q3

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NS FL 10 CP Q3

Post by kevinl » Sun Apr 07, 2019 3:41 am

Could you please explain how you came up with the trend ammonium >>potassium?
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Re: NS FL 10 CP Q3

Post by NS_Tutor_Will » Sun Apr 07, 2019 9:05 am

Thanks for the question!

To answer this one, we need to use the table that was given to us in the question stem. We see that characteristics leading to ionic bonds are low positive charge, large cation, and small anionic. Since we're looking to denature a protein, we'd want to use charge-charge interactions to take the protein out of its native, folded state (by promoting ionic interactions). Ammonium is larger than potassium and potassium is larger than sodium. Thus, according to the table, ADS > KDS > SDS when it comes to interacting ionically (and thus also when it comes to denaturing proteins).

I hope this helps!
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Re: NS FL 10 CP Q3

Post by menglunl » Thu Oct 31, 2019 3:46 pm

Hi, could you please explain how ammonium is bigger than potassium? Is it because ammonium is a charged molecule as opposed to just an ion?
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Re: NS FL 10 CP Q3

Post by NS_Tutor_Mathias » Fri Nov 01, 2019 2:56 pm

Ammonium (NH4+) is simply far bulkier than potassium, because of its 4 hydrogen bonds. Bond-lengths are generally greater than atomic radii, and so almost any molecule will beat a single atom or ion in size.

Also, as a point of terminology: Charged molecules are ions. So both NH4+ and K+ are ions.
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