Question

Question #4d493

Answer 1

The salt precipitates because sodium chloride is much less soluble in ethanol than it is in water. This happens because of the structure of ethanol, or `CH_3CH_2OH`.

The `"-OH"` functional group enables ethanol to hydrogen bond and interact with water molecules. However, the non-polar part of the molecule, which is represented by an ethyl group, `CH_3CH_2-`, will prevent ethanol from being able to keep the `Na^(+)` and `Cl^(-)` ions separated from each other in solution.

As a result, ethanol will react more with the water molecules than with the ions. This implies that fewer water molecules will be available to keep the aforementioned ions apart in solution `->` salt precipitates.

Less available water molecules to interact with the ions is equivalent to having an increase in the concentration of the ions in solution.

`"Less SOLVENT" => "INCREASED concentration of ions"`

If the solution is saturated, this will automatically result in the precipitation of the salt.