SB C/P #3

[betterfuture]

Shouldn't the answer be the Electric Field answer, (D)?

The question states what ALLOWS the ions to seperate, which would be the applied electric field. Or else they wouldn't move at all. Can someone explain?

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[laczlacylaci]

I definitely agree that the electric field between the 2 plates are uniform, its even stated in the key.

I think you use the answer and put it in the q-stem, it might help.
A uniform electric field does allow the ions to move away from the MALDI plate, but you need that difference in mass-charge ratio to actually separate them. With out that difference, your ions will just moving at the same velocity, not allowing for separation.

Its kind of like the polarity difference that allows molecules to have different Rfs on a TLC. If you put two molecules with the same polarity, then they will move away from the starting point, but they won't separate (have different Rfs)

Let me know if that helps.

 

[betterfuture]

Yeah. I think for me, it's the word that makes a difference.

What I was thinking was what allows them to separate as in what caused them to separate. But I see that they want them to separate to be able to distinguish them apart so that would mean related to their mass/charge ratio.