Sciencemadness Discussion Board

Is solubility of salts in Acetone predictable?

bolbol - 17-1-2015 at 13:10

I am really interested in the solvent/solute thing when water isnt involved.

I am trying to figure out how Acetone (and im talking about pure dry acetone) can disolve some stuff that ethanol cant and vice versa. Their structure is very similar, at least to me. I can't seem to find a pattern to figure out if some substance could be soluble in a given solvent, Acetone in this case.

If there is any method to figuring out if polarity will be strong enough for Acetone to dissolve a given substance, I'd really like to know/learn more about it.
Thanks

Zombie - 17-1-2015 at 15:22

I found this link awhile ago. It will not completely answer all your questions as to all the salts it will dissolve but instead it list groups of salts, and their compatibility/non compatibility.

I have found it very useful. It's also a PDF so it's handy...
http://onlinelibrary.wiley.com/doi/10.1002/9780470924891.app...

Hope it helps.

gdflp - 17-1-2015 at 15:50

He's asking about the solubility, your link is useful, but not for determining solubility. "Compatibility" is whether the two react to form an explosive, hazardous, or otherwise dangerous mixture/degradation. As the the OP one big difference between acetone and ethanol is that ethanol is an alcohol so it has hydrogen bonding, whereas ketones like acetone don't. This can either help or hinder solubility depending on the solute.

Zombie - 17-1-2015 at 18:48

Got it. Sorry it won't help for this.

bolbol - 20-1-2015 at 17:58

So im guessing there really isnt anything

kmno4 - 22-1-2015 at 05:17

Is solubility of salts in Acetone predictable ?

Generally - no.
But in cases of singly charged, large cations/anions salts, it is predictable, at least in theory.
Solubility depends (is defined by) on free energy of (solvated) ions in given solvent.
The values of ΔG are available in literature for few ions in different solvents, also in acetone. As I wrote - this is valid only for large, not highly charged ions. The smaller ions with, the stronger tendency for ion-pairing and specific interactions with solvent. The same is in case of larger charges. For example, you can predict solubility of KCl or NaClO4 in acetone, but for CaCl2 or MgSO4, it would be much harder to predict.

Dan Vizine - 24-1-2015 at 10:16

kmno4 is right, generally, just from first principles, no. There are too many subtle, and not-so-subtle, forces at play

However, you should not view acetone as being too similar to alcohols. Not that acetone doesn't have an acidic proton, it does, but the form that does is not the predominant species (if you're not familiar with keto-enol equilibria, try Wiki.). The OH bond is simply much more polar than the carbonyl group. Polarity isn't the only factor in play, but it's usually the biggest.

Thus, lower alcohols are much better at dissolving polar species (as you need to overcome the solid's crystal lattice energy) because they are more polar. Methanol is a special case. I've always seen it as the bridge between water and alcohols. Among the alcohols, it alone is capable of significant reaction rates with magnesium. It dissolves a lot of things. For slightly polar compounds, acetone can be superior.

Like dissolves like is apparently pretty damned true.

bolbol - 25-1-2015 at 23:25

Quote: Originally posted by kmno4  
Is solubility of salts in Acetone predictable ?

Generally - no.
But in cases of singly charged, large cations/anions salts, it is predictable, at least in theory.
Solubility depends (is defined by) on free energy of (solvated) ions in given solvent.
The values of ΔG are available in literature for few ions in different solvents, also in acetone. As I wrote - this is valid only for large, not highly charged ions. The smaller ions with, the stronger tendency for ion-pairing and specific interactions with solvent. The same is in case of larger charges. For example, you can predict solubility of KCl or NaClO4 in acetone, but for CaCl2 or MgSO4, it would be much harder to predict.




Could u go into more detail about the last part where u are comparing salts. And also when u talk about dissolving of common salts in acetone, do you mean partial solubility like Ca(OH)2 in water or full solubility such as NaCl in water