How to distinguish palmitic acid from lauric acid?

Question

I'm reacting either palmitic acid or lauric acid ($\ce{C16H32O2}$ or $\ce{C12H24O2}$) with $\ce{NaOH}$, sodium hydroxide.

I'm wondering if there's any way to tell which one of those two acids it is after I've already reacted it with NaOH. It has to be a relatively short process, as I won't have much time. I'm doing this for a lab.

In case you feel uncomfortable about what you may call "helping me cheat", please note that my assignment states that I can have online help:

You may look up information to complete your flow-chart, just be sure to cite your sources...

Note: it doesn't have to be NaOH, it could be any base, I just picked that one. If you think another one would work better, recommend that as well, please.

Answer 1

Consider the reaction which happens, what is produced and then what is different about the products? The key has to be in their properties.

The saponification reaction which takes place will produce a salt, in this case it will make sodium palmitate and sodium laurate. These two salts have very different solubilities and this makes a marked difference in the lathering ability. Sodium laurate is higher and thus lathers more readily.

For more details :

Solubility data

Saponification

Scientific Soapmaking: The Chemistry of the Cold Process By Kevin M. Dunn