Write the net ionic equation that describes the reaction that occurs when a solution of barium nitrate is added to a flask containing sulfate ions?

1 Answer
Jul 24, 2017

#"Ba"_ ((aq))^(2+) + "SO"_ (4(aq))^(2-) -> "BaSO"_ (4(s)) darr#


The idea here is that barium nitrate is a soluble ionic compound, which implies that it dissociates completely in aqueous solution to produce barium cations, #"Ba"^(2+)#, and nitrate anions, #"NO"_3^(-)#.

So when barium nitrate is dissolved in water, it exists as dissociated ions

#"Ba"("NO"_ 3)_ (2(aq)) -> "Ba"_ ((aq))^(2+) + 2"NO"_ (3(aq))^(-)#

When you mix this solution with a solution that contains sulfate anions, #"SO"_4^(2-)#, an insoluble solid that precipitates out of the solution will be produced. This insoluble solid is called barium sulfate, #"BaSO"_4#.

So you can say that when these two solutions are mixed, you have

#"Ba"_ ((aq))^(2+) + 2"NO"_ (3(aq))^(-) + "SO"_ (4(aq))^(2-) -> "BaSO"_ (4(s)) darr + 2"NO"_ (3(aq))^(-)#

Since the nitrate anions are present on both sides of the chemical equation, you can say that they are spectator ions.

This implies that you can eliminate them

#"Ba"_ ((aq))^(2+) + color(red)(cancel(color(black)(2"NO"_ (3(aq))^(-)))) + "SO"_ (4(aq))^(2-) -> "BaSO"_ (4(s)) darr + color(red)(cancel(color(black)(2"NO"_ (3(aq))^(-))))#

to get the net ionic equation, which looks like this

#"Ba"_ ((aq))^(2+) + "SO"_ (4(aq))^(2-) -> "BaSO"_ (4(s)) darr#

Barium sulfate is a white solid that will precipitate out of the solution.