When sodium sulfate (Na₂SO₄) reacts with barium chloride (BaCl₂), a double displacement reaction occurs, resulting in the formation of barium sulfate (BaSO₄), a white precipitate, and sodium chloride (NaCl), which remains dissolved in solution.

Here's the balanced chemical equation:

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

Here's a breakdown of what happens:

* Sodium sulfate (Na₂SO₄) and barium chloride (BaCl₂) are both soluble ionic compounds, meaning they dissolve in water and dissociate into their respective ions.

* The positively charged barium ions (Ba²⁺) from barium chloride combine with the negatively charged sulfate ions (SO₄²⁻) from sodium sulfate to form barium sulfate (BaSO₄). Barium sulfate is insoluble in water and therefore precipitates out of solution as a white solid.

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

This reaction is an example of a precipitation reaction because it results in the formation of an insoluble solid. It is also a metathesis reaction, which means that the cations and anions of the reactants switch partners.

Key characteristics of the reaction:

* White precipitate formation: The formation of barium sulfate as a white precipitate is a clear indication of the reaction.

* Exothermic reaction: The reaction releases heat, making it slightly exothermic.

This reaction is often used in laboratory settings to demonstrate precipitation reactions and to identify the presence of sulfate ions in a solution.