Can something that dissolves in water be hydrophobic?

[rwooduk]

This may be a really stupid question, but I'm going to go ahead anyway.

Say I have CO2 and dissolve it in water to give H2CO3, are / could the H2CO3 molecules be hydrophobic?

To put this in context I want to somehow drive the H2CO3 molecules to the surface of the liquid. Does this make sense? Would this be possible?

 

[Borek]

Does this make sense?

Not much. Whatever is dissolved is more or less uniformly distributed. Sure, there can be a concentration gradient, but that happens when there is no mixing and you either add or remove the substance on the solution surface. Otherwise it is unlikely.

 

[rwooduk]

Not much. Whatever is dissolved is more or less uniformly distributed. Sure, there can be a concentration gradient, but that happens when there is no mixing and you either add or remove the substance on the solution surface. Otherwise it is unlikely.

That's very helpful, thanks!

To be more specific, I am reading a paper that uses salt to increase the ionic strength of a liquid, so that hydrophobic organic pollutants in the liquid are driven to the surface. Please could you lend some insight into how this differs from the CO2 case above?

Again, apologies if this makes little sense.

 

[Borek]

https://en.wikipedia.org/wiki/Salting_out

 

[rwooduk]

https://en.wikipedia.org/wiki/Salting_out

Interesting. I see it has a similar method.

Do you know of any methods to make a particular molecule hydrophobic, so that it could be "salted out"?

 

[Borek]

I general you can't change properties of a molecule* without changing the molecule itself.

*At least for small, simple ones. when it comes to large ones like proteins things get more complicated, as a lot depends on what you mean by "changing" the molecule.

 

[rwooduk]

I general you can't change properties of a molecule* without changing the molecule itself.

*At least for small, simple ones. when it comes to large ones like proteins things get more complicated, as a lot depends on what you mean by "changing" the molecule.

Hm, that's unfortunate, but okay you have been very helpful, thanks again!