FL 3 C/P #1

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FL 3 C/P #1

Postby mshah » Sun Sep 10, 2017 3:40 pm

For #1, why wouldn't you be able to say entropy increases because it is going from a gel-ish solution to liquid and becoming more disorder? How are you supposed to know that you have to look at the table if it contradicts that?
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Re: FL 3 C/P #1

Postby NS_Tutor_Andrew » Sun Sep 10, 2017 10:03 pm

Hi mshah,

Thanks for the question! A couple of things to note here:

First off, the fact that Table 1 contains entropy values and the fact that the passage and question stem refer to liquid *crystals*, which is not a state of matter you're expected to be familiar with for the MCAT both suggest that you should consult passage information.

Second, and more importantly, the question starts off by asking "in the presence of a carbohydrate...". This means that you need to compare the ΔS and ΔH values of the solutions with a carbohydrate present (everything below the first row in the table) to the ΔS and ΔH values of the solution with NO carbohydrate present (the first row, labeled none). The ΔS and ΔH values in the first row (w/ no carbohydrate) are higher than the corresponding values in all the other rows, which indicate solutions with different types of carbohydrates, so it therefore makes sense to say that adding a carbohydrate decreases these values relative to a solution with no carbohydrate (corresponding to D).

It may also be helpful to observe that all the ΔS values are actually positive! This means that your intuition that going from a gel to a liquid crystal state would increase entropy is correct. The issue is that the question is asking you to *compare* those values across different solutions and draw a conclusion about the effects of carbohydrates.

Hope this is helpful!
Andrew D.
Content Manager, Next Step Test Prep.

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