Science, Tech, Math › Science Single Displacement Reaction Overview of a Single Displacement or Substitution Reaction Share Flipboard Email Print In a single displacement or substitution reaction, one element replaces another. Don Farrall, Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry in Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate by Anne Marie Helmenstine, Ph.D. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Updated March 06, 2017 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. Continue Reading