What is the difference between displacement and double displacement reactions? Write relevant equations for the above.

A displacement reaction is one when a more reactive substance displaces a less reactive one from its salt solution, whereas a double displacement reaction is one where a mutual exchange of ions happens between two compounds.

In a displacement reaction, only a single displacement takes place, whereas in the double displacement reaction, as the name suggests, two displacement takes place between the molecules.

Example:

Displacement reaction

Mg + 2HCl → MgCl2 + H2

Double displacement reaction

2KBr + BaI2 → 2KI + BaBr2