Chemical Reactions

DOUBLE DISPLACEMENT REACTIONS

A double displacement reaction is a type of reaction in which two reactants exchange ions to form two new compounds. Double displacement reactions typically result in the formation of a product that is a precipitate
Double displacement reactions take the form 
 
              AB(aq) + CD(aq)  \( \to \)  AD (aq)+ CB(aq).  
             

EXAMPLE
The reaction between silver nitrate and sodium chloride is a double displacement reaction. The silver trades its nitrite ion for the sodium's chloride ion, causing the sodium to pick up the nitrate anion.This is precipitation reaction where an insoluble solid AgCl is formed.
AgNO₃ + NaCl  \( \to \)   AgCl \( \downarrow \)+ NaNO₃

BaCl₂(aq) + Na₂SO₄(aq)  \( \to \)  BaSO₄(s) \(\downarrow \)+ 2 NaCl(aq)