Single Displacement Reactions

Another type of redox reaction is one in which an element replaces or displaces another from a compound. In these reactions, known as single replacement reactions, the element which replaces that which is in a compound is always oxidized. The element being displaced, is always reduced. This is illustrated by the displacement of hydrogen gas by metallic iron in the example below:

 

The oxidation of iron is represented by:


Note that the net charge on both sides of the arrow must always be equal to each other.

 

The reduction of hydrogen is represented by:


Note: In both oxidation and reduction, the net charge of both sides of the arrow must always be equal.

 

Another example is the replacement of silver by copper.


Note: Copper is oxidized; silver is reduced.