A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound.
A + BX -> B + AX
For example:
Cation Replacement
Zn + CuCl2 -> ZnCl2 + Cu
Anion Replacement
Br2 + 2Ki -> 2KBr + I2
You just switch either the cation with another anion or switch an anion with another cation.
