Solubility in ochem

[flin5845]

This comes from Chad's quizzes.

What is most soluble in benzene
A.CH3CH2CH2OH
B.CH3CH2OH
C.HOCH2CH2OH
D.CH3CH2CH2CH2CH2OH

I guess I understand that since they are all capable of H-bonding, they are all polar. Since D has the largest "non-polar" area, it will be most soluble.

Here is my question though, I initially looked all of the answers and saw they all had -OH but then I looked at C and saw that it was a symmetrical compound, and I assumed that the molecule would be non-polar overall. Thus being most soluble in benzene. How Chad explains it, I guess C would actually be the least soluble since it has multiple areas of H-bonding.

But is it not safe to say if a molecule is symmetrical it will be non-polar? Should I just go with if ANYTHING has hydrogen bonding, it will be polar?

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[pandalove89]

it's not C ?

 

[chippy]

you want to be looking at the intramolecular bonds, instead of the molecule's overall polarity. so although C may not have have an overall dipole, it still can hydrogen bond with other C's because of its polar OH bonds. While D also interacts with other D's by forming hydrogen bonds, it also interacts with other D's with more LDS than A, B, or C because of its large "non-polar" area, which is why it would best interact with benzene, whose intramolecular attractions are all LDS.

 

[chemistryguy]

This comes from Chad's quizzes.

What is most soluble in benzene
A.CH3CH2CH2OH
B.CH3CH2OH
C.HOCH2CH2OH
D.CH3CH2CH2CH2CH2OH

I guess I understand that since they are all capable of H-bonding, they are all polar. Since D has the largest "non-polar" area, it will be most soluble.

Here is my question though, I initially looked all of the answers and saw they all had -OH but then I looked at C and saw that it was a symmetrical compound, and I assumed that the molecule would be non-polar overall. Thus being most soluble in benzene. How Chad explains it, I guess C would actually be the least soluble since it has multiple areas of H-bonding.

But is it not safe to say if a molecule is symmetrical it will be non-polar? Should I just go with if ANYTHING has hydrogen bonding, it will be polar?

(C) is ethylene gylcol, its extremely polar because it has two hydroxyl groups, which are in general very polar. Forget about symmetry, that might only make a difference is very small molecules. Just look at structures. If there's a hydroxyl group, its pretty polar, if theres a carbonyl, its slightly polar. Of course, the larger the alkyl group, the more non polar it is.