Does a precipitate form when the aqueous solutions #"Ba(NO"_3)_2"# and #"2KOH"# are combined?
No, a precipitate will not form when barium nitrate, #Ba(NO_3)_2#, reacts with potassium hydroxide, #KOH#, in aqueous solution because both products are soluble in water.
The balanced chemical equation looks like this
#Ba(NO_3)_(2(aq)) + 2KOH(aq) -> Ba(OH)_2(aq) + 2KNO_3(aq)#
You are essentially dealing with a doppia reazione di sostituzione; in aqueous solution, both reactants will dissociate into ions.
L'equazione ionica completa è
#Ba_((aq))^(2+) + 2NO_(3(aq))^(-) + 2K_((aq))^(+) + 2OH_((aq))^(-) -> Ba_((aq))^(2+) + 2OH_((aq))^(-) + 2K_((aq))^(+) + 2NO_(3(aq))^(-)#
Notice that all the ions that are on the reactants' side can also be found on the products' side. This implies that all the species will exist as ions in solution and no precipitate will be formed.
A quicker way to determine whether or not a reaction will produce a precipitate is to look at the regole di solubilità. If you're familiar with these rules, you'll notice that both barium hydroxide, #Ba(OH)_2#, and potassium nitrate, #KNO_3#, are soluble in aquesous solution.
The solubility rules: