When we recrystallize a salt, #M^(+)X^-#, typically we would get an hydrate, i.e. something of the form #[M{(OH)_2}_6]^(+)X^-#. Note that there MAY be 6 so-called waters of crystallization. In inorganic synthesis often the chemist has to go to great lengths in drying the hydrated salt, i.e. to remove the waters of crystallization.
Now we have #M^(2+)# versus #M^(+)#. #"A priori"# we would expect that the dication would be more heavily hydrated than the monocation, inasmuch as the ion dipole interaction should be much stronger for the dication. Note that I speak generally and not specifically.
