A double displacement reaction is also sometimes called a double replacement reaction or salt metathesis reaction. It is a type of chemical reaction where two ionic compounds exchange ions to form two new ionic compounds.

Here are the main points:

• Reactants Involves two ionic compounds dissolved in a solution (usually water).
• Products: Two new ionic compounds are produced.
• During this reaction, positive ions (cations) and negative ions (anions) from the original compounds swap places, forming new ionic bonds.

Both cations and anions are displaced (replaced) in the reaction, that’s Why it’s called double displacement.

Example of a double displacement reaction

Let’s consider the reaction between Barium Chloride (BaCl₂) and Sodium Sulfate (Na₂SO₄):

• Reactants: BaCl₂ (Barium Chloride) and Na₂SO₄ (Sodium Sulfate)
• Products: BaSO₄ (Barium Sulfate) and NaCl (Sodium Chloride)

The chemical equation representing this reaction is:

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

Here, the Barium (Ba²⁺) ions from BaCl₂ swap places with the Sodium (Na⁺) ions from Na₂SO₄, forming Barium Sulfate (BaSO₄) as a precipitate (solid) and Sodium Chloride (NaCl) which remains dissolved in the aqueous solution (aq).