What is the relationship between solubility, ionic association and solvation of an electrolyte in a mixed medium and how does it vary with the increase or decrease of the dielectric constant of the medium? Bibliography, please.
I will put my question in a simpler way with an example.
The solubility of NaCl in pure water at 25ºC is approximately 6.14 moles/L.
I try to dissolve NaCl at 25ºC in equimolar mixtures (suppose X=0.50) of water + co-solvent and the solubility always decreases a lot (more the more co-solvent there is present).
This was known for aqueous mixtures of methanol, ethanol, propanol, acetone, DMF, etc. (all with lower dielectric constant than water and therefore also the mixture).
Now if I do the same with EC, formamide, N-methyl-formamide, N-methyl-acetamide, N-methyl-acetamide, .... (all with dielectric constant greater than water and therefore the mixture also) the same thing happens.
Does this mean that the dielectric constant of the medium does not influence the solubility?
If I have proven that it influences the ionic association or the primary hydration number, but not the solubility (the solubility product, the increased energy of Gibbs' transference,....) Why?
The same thing happens with all alkaline halides (and I imagine that in the other salts?
Another example to finish: for example, the solubility of NaF in water at 25ºC is 0.983 moles/L. What do I have to do to increase it?
Translated with www.DeepL.com/Translator
I was recently reading pg. 62-64 of "Intermolecular and Surface Forces" (3rd edition) of Jacob N. Israelachvili, and he presentes a nice plot of the solubility of NaCl or glycine (in logaritm scale) vs. 1/(dielectric constant) and a linear increase of the solubility for solvents with high dielectric constant is verified. Since this data is for pure solvents, and in this case the solubility is reasonably explained in terms of dielectric constant changes (he uses a simplified model to explain the main trend of the curve), I would suggest that what is somewhat dominating the observations you are making is the interactions between the solvent molecules of different types. The association and redistribuion might decrease the cabability they have, individually (as pure solvents), to solvate the ions. It is just a suggestion, and I think other factors might be important as well (from polarizability of the solventes to their pure densities, for instance), but the plot made me think on this direction above all.
Thank you for your kind reply.
If it were not an intellectual property "crime", you could send me pg. 62-64 of "Intermolecular and Surface Forces" (3rd edition) of Jacob N. Israelachvili. We don't have it in our library.
But there is something I can do within the law. The google books make some pages of this book available, and pgs. 62-64 are included! I found it here: https://books.google.com.br/books?id=MVbWBhubrgIC&printsec=frontcover&hl=pt-BR&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
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