The reaction that occurs when an aqueous solution of BaCl₂ is added to Na₂SO₄ is a double displacement reaction that results in the formation of a precipitate.

Here's the breakdown:

* Reactants:

* Barium chloride (BaCl₂): A soluble ionic compound.

* Sodium sulfate (Na₂SO₄): A soluble ionic compound.

* Products:

* Barium sulfate (BaSO₄): An insoluble ionic compound (precipitate).

* Sodium chloride (NaCl): A soluble ionic compound.

* Reaction Equation:

BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

Explanation:

When the solutions are mixed, the barium ions (Ba²⁺) from BaCl₂ and sulfate ions (SO₄²⁻) from Na₂SO₄ combine to form barium sulfate (BaSO₄), which is insoluble in water. This means that BaSO₄ will precipitate out of the solution as a white solid.

The remaining ions, sodium (Na⁺) and chloride (Cl⁻), remain dissolved in the solution as sodium chloride (NaCl).

Key Observations:

* The formation of a white precipitate (BaSO₄) is a clear indication of this reaction.

* The solution may also appear cloudy as the precipitate forms.

This reaction is a classic example of a precipitation reaction, where two soluble ionic compounds react to form an insoluble ionic compound.