Question

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?

Answer 1

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

Explanation:

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.