Question

What is meant by a double displacement reaction? Explain with the help of one example.

Answer 1

The reactions in which two compounds react by an exchange of ions to form two new compounds are called double displacement reactions. A double displacement reaction usually occurs in solution, and one of the products, being insoluble, precipitates out (separates as a solid).

When a silver nitrate solution is added to a sodium chloride solution, a white precipitate of silver chloride forms along with a sodium nitrate solution.

\[\ce{\underset{Silver nitrate}{AgNO3_{(aq)}} + \underset{Sodium chloride}{NaCl_{(aq)}} -> \underset{(White ppt{.})}{\underset{Silver chloride}{AgCl_{(s)}}} + \underset{Sodium nitrate}{NaNO3_{(aq)}}}\]