Why is ethanol a better solvent than water for crystallization?

Question

Why is ethanol a better solvent than water for crystallization?

Answer 1

Ethanol is used in some applications because the compound is not soluble in water. It is more volatile than water and evaporates off easily. It all depends on the electronegativity of the compound. Ethanol has a negative polarity due to it's polyatomic structure (CH3 CH2 OH).  The hydroxide has a -1 charge. Organic compounds containg a hydroxyl are known as alcohols. Water (H2O) is unusual in that it has a large negatively charged oxygen and two small positively charged hydrogens. Because water has been around for billions of years, it has become a matrix for organisms to develop and a lot of compunds are soluble in it. But today there are products that are not evolved in the presence of water and arn't as soluble if at all in water. An example would be the seperation of starcth and acetylsalicylic acid in aspirin. both compound are soluble in water but starch is not soluble in ethanol. When the powered mixture is poured into hot ethanol and allowed to cool, the starch will settle to the bottom and can be seperated from the acetylsalicylic acid/ethanol solution in a separatory funnel. And the acetylsalicylic acid can be isolated by boiling away the ethanol. It all depends on the atomic bonds of the compound and solvent. Hope this helps.

Answer 2

Depends on what you're crystallizing, LOL.

Anyways, lots of things dissolve MUCH better in water than in ethanol.  So adding ethanol to a water solution of ... something... will cause the something to leave solution if it's not particularly soluble in ethanol.

Answer 3

It depends on what you want to (re)crystallize. You can knock polysaccharides and other sparingly soluble compounds out of aqueous solution by adding ethanol.

Water is of course a better overall solvent than ethanol, so you could say that makes it better for (re)crystallization because if something does not dissolve in the first place, you cannot crystallize it out!

Once again, IT DEPENDS!

Answer 4

yes. add ethanol 10 mL at  a time until the solids are dissolved.