Single displacement reaction

Single displacement reaction

A single-displacement reaction, also called single-replacement reaction, is when an element or ion moves out of one compound and into another. (One element is replaced by another in a compound.) This is usually written as :A + BX → AX + BThis will occur if A is more reactive than B. You can refer to the reactivity series to be sure of this.

A and B must be either:
*different metals (hydrogen's behavior as a cation renders it as a metal here), in which case X represents an anion; or
*halogens, in which case X represents a cation.In either case, when AX and BX are aqueous compounds (which is usually the case), X is a spectator ion.

Due to the free state nature of A and B, all single displacement reactions are also oxidation-reduction reactions. When A and B are metals, A is always oxidized and B is always reduced. Since halogens prefer to gain electrons, A is reduced (from a 0 to −1) and B is oxidized (from −1 to 0) when A and B represent those elements.

A and B may not have the same charge when ions are formed therefore some balancing of the equation may be necessary. For example the reaction between silver nitrate, AgNO3, and zinc, Zn, forms silver, Ag, and zinc nitrate, Zn(NO3)2.

:2AgNO3(aq) + Zn(s) → 2Ag(s) + Zn(NO3)2(aq)

All simple metal with acid reactions are single displacement reactions. For example the reaction between magnesium, Mg, and hydrochloric acid, HCl, forms magnesium chloride, MgCl2, and hydrogen, H2.

:Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

Cation replacement

One cation replaces another. A cation is a positively charged ion or a metal. When it is written in generic symbols, it is

AX + Y → YX + A

Element Y has replaced A (in the compound AX) to form a new compound YX and the free element A. This is an oxidation-reduction reaction wherein element A is reduced from a cation into the elemental form and element Y is oxidized from the elemental form into a cation.Some examples are:
# Cu + 2AgNO3 → 2Ag + Cu(NO3)2
# Fe + Cu(NO3)2 → Fe(NO3)2 + Cu
# Ca + 2H2O → Ca(OH)2 + H2
# Zn + 2HCl → ZnCl2 + H2

Anion replacement

One anion replaces another. An anion is a negatively charged ion or a nonmetal. Written using generic symbols, it is:

A + XY → XA + Y

Element A has replaced Y (in the compound XY) to form a new compound XA and the free element Y. This is an oxidation-reduction reaction wherein element A is reduced from the elemental form into an anion and element Y is oxidized from an anion into the elemental form.

Some of the only examples that involve halogens are here, so here are the two examples:
# Cl2 + 2NaBr → 2NaCl + Br2
# Br2 + 2KI → 2KBr + I2

ee also

*Double displacement reaction


Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Displacement — may refer to: Contents 1 Physical sciences 1.1 Physics 1.2 Engineering …   Wikipedia

  • Salt metathesis reaction — Salt metathesis (from the Greek μετάθεσις transposition ) is a molecular process involving the exchange of bonds between the two reacting chemical species, which results in the creation of products with similar or identical bonding… …   Wikipedia

  • Metathesis reaction — Metathesis is a bimolecular process involving the exchange of bonds between the two reacting chemical species, which results in the creation of products with similar or identical bonding affiliations. [International Union of Pure and Applied… …   Wikipedia

  • reaction mechanism — Introduction       in chemical reactions (chemical reaction), the detailed processes by which chemical substances are transformed into other substances. The reactions themselves may involve the interactions of atoms (atom), molecules (molecule),… …   Universalium

  • Chemical reaction — Chemical reactions redirects here. For the 2007 television episode, see Chemical Reactions (Men in Trees). A thermite reaction using iron(III) oxide. The sparks …   Wikipedia

  • Multiple displacement amplification — (MDA) is a non PCR based DNA amplification technique. This method can rapidly amplify minute amount of DNA samples to reasonable quantity for genomic analysis. The reaction starts by annealing random hexamer primers to the template and DNA… …   Wikipedia

  • ion-exchange reaction — ▪ chemical reaction Introduction       any of a class of chemical reactions between two substances (each consisting of positively and negatively charged species called ions (ion)) that involves an exchange of one or more ionic components.… …   Universalium

  • Adverse drug reaction — Classification and external resources Adverse drug reaction leading to hepatitis (drug induced hepatitis) with granulomata. Other causes were excluded with extensive investigations. Liver biopsy …   Wikipedia

  • Polymerase chain reaction optimization — The polymerase chain reaction (PCR) is a commonly used molecular biology tool for amplifying DNA, and various techniques for PCR optimization have been developed by molecular biologists to improve PCR performance and minimize failure. Contents 1… …   Wikipedia

  • protein — proteinaceous /proh tee nay sheuhs, tee i nay /, proteinic, proteinous, adj. /proh teen, tee in/, n. 1. Biochem. any of numerous, highly varied organic molecules constituting a large portion of the mass of every life form and necessary in the… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”