[hosseini_157]

Dear friends,

I had a critical ambiguity regarding the effect of polar solvents on salt solubility. For example, I add NaCl to water and make a solution. After that, I add a less polar solvent such as methanol, the salt starts to precipitate. From the chemistry point of view, is it related to the rate of reaction (Gibbs free energy) and to be described in this way, or it is not associated with this concept. Or adding this solvent just affect the instability of reactant and transition state the solution?

Thanks.

[Arkcon]

Dear friends,

I had a critical ambiguity regarding the effect of polar solvents on salt solubility. For example, I add NaCl to water and make a solution. After that, I add a less polar solvent such as methanol, the salt starts to precipitate.

Well, on a level, its a simple concept of reduced solubility the the second solvent you chose.  But let's treat the rest of your question.

From the chemistry point of view, is it related to the rate of reaction (Gibbs free energy) and to be described in this way,

Well, if we're going to use Gibbs free energy of a reaction.  We should describe the two systems: solution of NaCl in water, solution of NaCl in methanol, and compare.  (And of course, the new, mixed system isn't really described by either.)  However, more troubling for me -- can we describe dissolving a salt as a reaction?

or it is not associated with this concept.

As I said I above, I don't think so.  But it has to be described that way, if we want to consider it so.

Or adding this solvent just affect the instability of reactant and transition state the solution?

That can be another way top describe the system. But again, I can't be sure its pertinent.  Can you find a textbook that describes dissolving in this way?  How do textbooks describe the dissolving of salts?

Thanks.

[Corribus]

However, more troubling for me -- can we describe dissolving a salt as a reaction?

What's a reaction?  From a thermodynamic sense, is the distinction important?