Displacement Reaction: Definition, Example, Types, Uses, and Reactivity Series

Displacement Reaction Overview

Displacement reactions are extremely significant chemistry processes. They are employed in a variety of sectors. For example, we employ electroplating, which is based on displacement reactions, to keep iron items from rusting.

Displacement Reaction Definition

The sort of chemical reaction in which the atom of the more reactive element(s) displaces the atom of the less reactive element(s) from its compound is known as a displacement reaction. Metals and nonmetals both undergo displacement reactions. It is also known as a substitution reaction. A displacement reaction occurs when an atom or a group of atoms in a molecule is displaced by another atom.

Displacement Reaction Examples

Consider two persons, each carrying one basket of apples. The first guy has room for three apples to entirely fill his basket, whereas the second person's basket is already overflowing with three apples. So they both work together to create a stable and balanced environment for both of them by providing the first person with an additional three apples. Similarly, two elements swap positions in their compounds to create a better and more stable molecule. 

When iron is introduced to a copper sulfate solution, for example, it displaces the copper metal.

A + B-C → A-C + B

When A is more reactive than B, the above equation exists. A and B must be either-

1. Halogens in which C denotes a Cation.
2. Different metals, where C represents an anion. 

Read more about the SI Unit of Displacement.

Types of Displacement Reaction

The following are two types of displacement reactions-

Single Displacement Reactions

A single displacement reaction, also known as a single replacement reaction, is a type of oxidation-reduction chemical reaction in which an ion or element moves out of a molecule, replacing one element with another.

For Example- 

2 HCl(aq) + Zn(s) → ZnCl2(aq) + H2(g)

In this sort of displacement reaction, one free element replaces the other element from its compound to generate a new element and compound. Instead of both being compounds, one free element and one compound are usually present in this reaction-

A + B-C → A-C + B

This reaction happened only because the element "A" is more reactive than B; as a result, a more stable molecule, A-C is created as a result of this reaction. A and B must be separate metals or halogens in this reaction. If they are different metals,"C" becomes an anion; if both A and B are halogens, "C" becomes a cation. 

For Example- 

CaI₂(s) + Cl₂(g) → CaCl₂(s) + I₂(s)

This reaction will occur because chlorine, abbreviated "Cl," is more reactive than iodine, abbreviated "I." These are both halogens, and the rule states that "the halogens at the top of the periodic table in their group can replace the halogens below them, but not the other way around."  As "Br" is located below Fluorine in the periodic table, 

CaF₂(s) + Br₂(l) CaBr₂(s) + F₂(g) is not conceivable.

Read more about the First 20 Elements of the Periodic Table.

Double Displacement Reactions

Double displacement reactions occur when a portion of two ionic compounds is transferred, resulting in the formation of two new components. A twofold displacement reaction has the following pattern. Double displacement reactions occur mostly in aqueous solutions, where ions precipitate and exchange ions. We saw in the single displacement reaction that there is one compound and one free element, and the free element, being more reactive, replaces an element in the compound to generate one new compound and one new free element. In a twofold displacement reaction, however, two compounds react with each other and swap components to generate two new elements. Ionic or covalent bonds exist between the two interacting chemicals in their aqueous solutions. After the reaction has precipitated, it generally produces only one product. A general double displacement reaction happens as follows-

A-B + C-D → A-D + C-B

In the beginning, molecules A-B and C-D in an aqueous solution react to form new compounds A-D and C-B. This basic example can help us understand why this reaction occurred. 

For Example: Two males and two females enroll in a dance class and are expected to form a relationship. They create a couple at random as A-B and C-D. However, the dance instructor discovers that A is more at ease with D and B is more at ease with C. As a consequence, they swap partners to form new pairings like A-D and C-B based on their comfort, which would yield better outcomes. Similarly, in order to achieve a more stable state, elements create compounds with other elements. 

Read more about the Father of Chemistry.

Uses of Displacement Reaction

The following are some of the uses of displacement reaction-

Iron Ore Extraction

Iron may be extracted from its ore by interacting with carbon.

Read more about the Valency of Carbon.

Metals are Extracted

A displacement process can be used to extract other metals, such as chromium.

Neutralization of Acids

The formation of HCl acid in our stomach causes indigestion. Antacids include a base that induces a displacement reaction in the body.

Welding using Thermite

Aluminum (Al) and ferric oxide (Fe2O3) alloys are used to weld railroad joints together.

What is the Reactivity Series?

The reactivity series is a grouping of metals ordered by reactivity from highest to lowest. As a result, the metal reactivity series may be characterized as a sequence of metals arranged in decreasing order of reactivity. It is often referred to as an activity series. Metals' reactivity is caused by either their incomplete outer orbitals or their electrical structure. Metals lose electrons and generate positively charged ions. Metals with higher atomic numbers are more reactive because their electrons are farther away from the positively charged nucleus. As a result, they may simply be removed. The following table Gives details about the symbol, name, and nature of elements-

Although hydrogen is a nonmetal, it has been included in the reactivity series because it aids in the comparison of metal reactivity.