Why are inorganic sodium salts much better soluble in ethanol than potassium salts?
The reason seems to be : - Ionization potential of pottasium is lower than that of sodium ,thereore potassium salts are more polar as compared to sodium salts; - Potassium being more reactive than the sodium reacts faster withbwater,
Potassium's lone electron is much more easily transferred to produce a potassium ion than is sodium's because of its electronic structure so that any potassium salt is more ionic in nature than is its analogous sodium counterpart. Since ethanol is not very acidic (polar) it solublizes less polar materials preferentially over more polar ones. Therefore, sodium salts will, generally, be more soluble in ethanol than will be potassium analogs.
Sodium ions are smaller cations than potassium ions. Ethanol has a polar bond in the OH, but it also has a nonpolar tail, the ethyl group. So, unlike water, that has two OH groups that are polar and can interact with cations, ethanol has only one, so it requires strong electrostatic attractions to form a hydrogen bond - dipole interaction with any cation that it encounters. Being smaller, the sodium ions have their positive charge concentrated over a much smaller volume, so the polar OH bond in ethanol is more strongly attracted to the concentrated charge of the sodium than to the diffuse charge of the potassium ion, making the salt more soluble in this solvent.
