Single Displacement Reaction

Overview of a Single Displacement or Substitution Reaction

In a single displacement or substitution reaction, one element replaces another.
In a single displacement or substitution reaction, one element replaces another. Don Farrall, Getty Images

A single displacement reaction or substitution reaction is a common and important type of chemical reaction. A substitution or single displacement reaction is characterized by one element being displaced from a compound by another element.

A + BC → AC + B

A single displacement reaction is a specific type of oxidation-reduction reaction. An element or ion is replaced by another in a compound.

Single Displacement Reaction Examples

An example of a substitution reaction occurs when zinc combines with hydrochloric acid.

The zinc replaces the hydrogen:

Zn + 2 HCl → ZnCl2 + H2

Here is another example of a single displacement reaction:

3 AgNO3 (aq) + Al (s) → Al(NO3)3 (aq) + 3 Ag (s)

How To Recognize a Substitution Reaction

You can recognize this type of reaction by looking for a trade between one cation or anion in a compound with a pure substance in the reactants side of the equation, forming a new compound in the products side of the reaction.

If, however, two compounds appear to "trade partners", then you're looking at a double displacement reaction rather than a single displacement.

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Helmenstine, Anne Marie, Ph.D. "Single Displacement Reaction." ThoughtCo, Jun. 10, 2016, thoughtco.com/single-displacement-reaction-604039. Helmenstine, Anne Marie, Ph.D. (2016, June 10). Single Displacement Reaction. Retrieved from https://www.thoughtco.com/single-displacement-reaction-604039 Helmenstine, Anne Marie, Ph.D. "Single Displacement Reaction." ThoughtCo. https://www.thoughtco.com/single-displacement-reaction-604039 (accessed May 23, 2018).