A double displacement reaction is a type of chemical reaction in which two compounds exchange ions to form two new compounds. A classic example of a double displacement reaction is the reaction between sodium chloride (NaCl) and silver nitrate (AgNO3) to form sodium nitrate (NaNO3) and silver chloride (AgCl). The chemical equation for this reaction is:

NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

In this reaction, the sodium and silver ions switch places, forming two new compounds.