Science, Tech, Math › Science Single-Displacement Reaction Definition and Examples What You Need to Know About Single-Displacement Reactions Share Flipboard Email Print Westend61 / Getty Images Science Chemistry Chemical Laws Basics 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. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College 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. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated June 27, 2019 The four main types of chemical reactions are synthesis reactions, decomposition reactions, single-displacement reactions, and double-displacement reactions. Single-Displacement Reaction Definition A single-displacement reaction is a chemical reaction where one reactant is exchanged for one ion of a second reactant. It is also known as a single-replacement reaction. Single displacement reactions take the form: A + BC → B + AC Single-Displacement Reaction Examples The reaction between zinc metal and hydrochloric acid to produce zinc chloride and hydrogen gas is an example of a single-displacement reaction: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g) Another example is the displacement of iron from an iron(II) oxide solution using coke as a carbon source: 2 Fe2O3 (s) + 3 C (s) → Fe(s) + CO2 (g) Recognizing a Single-Displacement Reaction When you look at the chemical equation for a reaction, a single-displacement reaction is characterized by one cation or anion trading places with another to form a new product. It's easy to spot when one of the reactants is an element and the other is a compound. Usually, when two compounds react, both cations or both anions will change partners, producing a double-displacement reaction. You can predict whether a single-displacement reaction will occur by comparing the reactivity of an element using an activity series table. In general, a metal can displace any metal lower in the activity series (cations). The same rule applies to halogens (anions).