Organic Solubility and BP

[surfingbhudda]

AAMC 8 #123: They say fatty acid salts are partially water-soluble because of the carboxylate anion, but it's my understanding that the hydrophobic portion of the molecule would outweigh this greatly. Was anybody else really bothered by that question? In general, how do you go about figuring out what layer (polar or nonpolar) a certain molecule will be in during extractions?

If you mix two liquids, one with a BP of say 50K and another of 60K, and when they are mixed, they interact favorably and give off heat, does that mean the BP can be elevated to above 60K? I know this affects vapor pressure, but not sure about boiling point.

Thanks!

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[MedPR]

AAMC 8 #123: They say fatty acid salts are partially water-soluble because of the carboxylate anion, but it's my understanding that the hydrophobic portion of the molecule would outweigh this greatly. Was anybody else really bothered by that question? In general, how do you go about figuring out what layer (polar or nonpolar) a certain molecule will be in during extractions?

If you mix two liquids, one with a BP of say 50K and another of 60K, and when they are mixed, they interact favorably and give off heat, does that mean the BP can be elevated to above 60K? I know this affects vapor pressure, but not sure about boiling point.

Thanks!

You're right about fatty acids typically being hydrophobic. However, depending on your answer choices, a fatty acid salt could be the most water soluble of the available answers. If you have a short chain fatty acid salt, it will be more soluble than a long chain fatty acid salt.