What is the difference between single displacement reaction double displacement reaction?

Single displacement reaction

Double displacement reaction

When a highly active element drives out a less active one from a molecule, the reaction is called a displacement reaction.

A twofold displacement reaction is one in which there is an ion exchange between the reactants.

The general reaction is,

A + B – C → A – C + B

The general reaction is,

AB + CD → AC + CB

Example: Reaction between Copper sulphate and Zinc granules

Example: Reaction between Lead nitrate and Potassium iodide

When zinc granules are combined with copper sulphate, which has a blue colour, the result is copper metal and zinc sulphate.

Potassium nitrate and lead iodide are the byproducts of the reaction between potassium iodide and lead nitrate solution.

Copper is displaced from the copper sulphate solution by zinc because zinc is more reactive than copper.

Since ion exchange occurs between the two reactants. Thus, this serves as an illustration of a twofold displacement reaction.

The chemical reaction that balances is as follows:

Zn (s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

Here is the chemical reaction:

2KI(aq) + Pb(NO3)2 (aq) → 2KNO3(aq) + PbI2(s)