(Ionic salts are a good example: usually they have strong interactions in the solid and solvated states.) If the interactions in the solid are weak, the compound can still be insoluble in polar solvents if the interactions with the solvent are weaker than the Coulomb interactions of the solvent molecules with other solvent molecules. For instance, if it has very strong interactions between molecules or ions in the solid state, then it won't be very soluble unless the solvation interations are also very strong. Solubility depends on the relative stability of the solid and solvated states for a particular compound. (It's also a little funny because many salts aren't strong electrolytes, so teachers might be telling their students to write an equation that doesn't show what's really happening.) However, it does help show what it means to be a spectator ion, since they are the same on both sides when you write it like this. Example: When the ferric chloride ( FeCl3) solution is added to the precipitate of ferric hydroxide ( Fe (OH)3 ), the hydroxide is dispersed into the.
Each particle of the precipitate has two layers, in primary layer certain ions are adsorbed and in the outer layer other ions of opposite charge are adsorbed. With some precipitates, peptization occurs during washing. The electrolyte is a stabilizing agent and basically called a peptizing agent. Problems with surface adsorption may be reduced by careful washing of the precipitate. No real chemist would be likely to do this because it is a nuisance. The conversion of precipitate into colloidal solution by adding a suitable electrolyte is called peptization. The precipitate (product) formed out from any chemical reaction always contains some traces of unwanted materials (unreacted reactants or catalyst and certain impurities).
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