Ethanol has that OH group. It’s a polar molecule, and a small one. But take two pure long-chained fatty acids, mix well, and then what will happen? (I said “oils” to show I didn’t mean a “hydrophobic in polar” solution, which I hadn’t thought the question implied.)
Gasoline is an excellent example of this behavior. It consists of a mixture of many different non-polar hydrocarbons with varying densities, some of which would be gaseous outside of solution. It stays mixed indefinitely (assuming you don’t let the volatile parts escape) because separation would require a reduction in entropy.
Ethanol has that OH group. It’s a polar molecule, and a small one.
Yes, I was just mentioning it as an example.
But take two pure long-chained fatty acids, mix well, and then what will happen?
I guess they stay mixed. They are pretty similar molecules, so the forces that hold e.g. oleic acid molecules together so that it doesn’t evaporate (Van der Waals, I think?) can just as well hold oleic acid molecules to e.g. linoleic acid molecules. (Whereas since water molecules and oleic acid molecules are pretty different, the force between a water molecule and an oleic acid molecule is a lot smaller than between two water molecules or two oleic acid molecules.)
Ethanol has that OH group. It’s a polar molecule, and a small one. But take two pure long-chained fatty acids, mix well, and then what will happen? (I said “oils” to show I didn’t mean a “hydrophobic in polar” solution, which I hadn’t thought the question implied.)
Gasoline is an excellent example of this behavior. It consists of a mixture of many different non-polar hydrocarbons with varying densities, some of which would be gaseous outside of solution. It stays mixed indefinitely (assuming you don’t let the volatile parts escape) because separation would require a reduction in entropy.
Thank you! That’s neat.
Yes, I was just mentioning it as an example.
I guess they stay mixed. They are pretty similar molecules, so the forces that hold e.g. oleic acid molecules together so that it doesn’t evaporate (Van der Waals, I think?) can just as well hold oleic acid molecules to e.g. linoleic acid molecules. (Whereas since water molecules and oleic acid molecules are pretty different, the force between a water molecule and an oleic acid molecule is a lot smaller than between two water molecules or two oleic acid molecules.)