BaCl2(aq) + Na2(SO4) (aq) ————> 2NaCl(aq) + BaSO4(white ppt.).
This reaction is known as double displacement and precipitation reaction

Reaction between Aqueous Barium Chloride and Aqueous Sodium Sulphate:
Barium chloride (BaCl2) is a soluble salt that dissociates into Ba2+ and Cl- ions when dissolved in water. Sodium sulphate (Na2SO4) is also a soluble salt that dissociates into Na+ and SO4^2- ions in water. When these two solutions are mixed, a double displacement reaction occurs.

Double Displacement Reaction:
- BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)
- In this reaction, the Ba2+ ion from barium chloride combines with the SO4^2- ion from sodium sulphate to form insoluble barium sulphate (BaSO4) as a white precipitate. This precipitate is not soluble in water and can be seen as a solid in the reaction mixture.
- The sodium ion (Na+) from sodium sulphate combines with the chloride ion (Cl-) from barium chloride to form sodium chloride (NaCl), which remains soluble in water and stays in the solution.

Explanation:
- The reaction is a double displacement reaction where the positive ions of the two reactants switch places to form new compounds.
- Barium sulphate is insoluble in water and precipitates out of the solution, while sodium chloride remains in the solution as ions.
- This reaction can be used to test for the presence of sulphate ions in a solution since barium sulphate is a characteristic precipitate for sulphate ions.
- The balanced chemical equation shows the stoichiometry of the reaction and the formation of the products.
In conclusion, the reaction between aqueous barium chloride and aqueous sodium sulphate results in the formation of insoluble barium sulphate and soluble sodium chloride through a double displacement reaction.