In a displacement reaction, a more reactive element replaces a less reactive element from a compound. In a double displacement reaction, two atoms or a group of atoms switch places to form new compounds.
Explaination:
Displacement chemical reaction :
A displacement reaction is the one wherein the atom or a set of atoms is displaced by another atom in a molecule. For instance, when iron is added to a copper sulphate solution, it displaces the copper metal.
Fe + CuSO4 → FeSO4 + Cu. When zinc is added to a copper sulphate solution, it displaces the copper metal. ...
Zn + CuSO4 → ZnSO4 + Cu.
etc.
Double Displacement Chemical Reaction :
Double displacement reactions take place mostly in aqueous solutions wherein the ions precipitate and exchange of ions takes place. For example, when a solution of barium chloride is mixed with sodium sulphate, a white precipitate of barium sulphate is formed rapidly. These reactions are ionic in nature.
Here are some examples of double displacement reaction: AgNO 3 + NaCl → AgCl + NaNO.
2NaCl + CaSO4 → Na2SO4+ CaCl.
H2SO4 + 2LiOH ⇌ Li2SO4 + 2H2O.