Question

(c) Write the balanced equation for the following chemical reaction:

Barium chloride + Aluminium sulphate$\to$Barium sulphate + Aluminium chloride

Answer 1

Double displacement reactions

Reactions in which exchange of ions takes place within the solution are called double displacement reactions. When two aqueous solutions of metals salts are mixed, the anion is exchanged between the metal ions to form new products. They are called double displacement reactions because both the metals are displaced from its aqueous solution. Some of the precipitation and neutralization reactions occur by double displacement.

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Reaction between Barium chloride and Aluminium sulphate

When an aqueous solution of Barium chloride (BaCl₂) is added to Aluminium sulphate [Al₂(SO₄)₃] solution, the sulphate ions and chloride ions are exchanged between the metals to form Barium sulphate (BaSO₄) and Aluminium chloride (AlCl₃).

The balanced equation for the reaction is:

$3BaC{l}_2\left(aq\right)+A{l}_2{\left(S{O}_4\right)}_3\left(aq\right)\to 3BaS{O}_4\left(s\right)+2AlC{l}_3\left(aq\right)$

(Barium (Aluminium (Barium (Aluminium

chloride) sulphate) sulphate) chloride)

Barium sulphate is a solid and therefore is precipitated from the solution and Aluminium chloride remains in the solution. Since a solid precipitate is formed from two aqueous solutions, this reaction is an example for precipitation reaction by double displacement.