Displacement Reactions - Definition, Types, Applications, FAQs

Displacement Reaction

Single Displacement Reaction

Single displacement reactions are those in which one element replace another element from its compound. Single replacement reactions are another name for this type of reaction.

$A+B-C \rightarrow A-C+B$

Example: $\mathrm{Zn}+\mathrm{CuSO}_4 \rightarrow \mathrm{ZnSO}_4+\mathrm{Cu}$

This is a single displacement reaction in which zinc is more reactive than copper, thus zinc displaces the copper from copper sulfate and forms zinc sulfate and copper.

Double Displacement Reaction

Double displacement reaction definition: Double displacement reaction are those in which two chemicals react by exchanging ions to produce two new molecules. Positive ions exchange negative ion partners in double replacement processes. Ionic chemicals dissolved in water undergo a lot of double displacement processes. The general equation represents a twofold replacement reaction.

$\mathrm{AB}+\mathrm{CD} \rightarrow \mathrm{AC}+\mathrm{BD}$

Atoms from two distinct compounds swap positions in a double displacement process. Two chemicals serve as reactants, while two compounds serve as products. Consider the following scenario: $\mathrm{Fe}_2 \mathrm{O}_3+6 \mathrm{HCl} \rightarrow 2 \mathrm{FeCl}_3+3 \mathrm{H}_2 \mathrm{O}$

Types of Displacement Reaction

Neutralisation Reaction: The acid-base process produces salt (which is naturally neutral) and water. For example, sodium chloride and water are generated when an aqueous solution of hydrochloric acid is mixed with an aqueous solution of sodium hydroxide.

$\mathrm{NaCl}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{NaOH}+\mathrm{HCl}$

Precipitation reaction: The precipitate is generated in a solution during chemical reaction in this reaction. When silver nitrate and sodium chloride are mixed in water, a white curdy silver chloride precipitate is created.

$\mathrm{AgNO}_3+\mathrm{NaCl} \rightarrow \mathrm{AgCl}_2+\mathrm{NaNO}_3$

Applications of Displacement Reaction:

Welding with thermite: The reaction of aluminium and ferrous oxide to produce molten iron, which is used to weld rail rails.

$2 \mathrm{Al}+\mathrm{Fe}_2 \mathrm{O}_3 \rightarrow \mathrm{Al}_2 \mathrm{O}_3+2 \mathrm{Fe}$

Aluminum is placed above the iron in the reactive series, thus aluminum is more reactive than iron which displaces iron from iron oxide to form aluminum oxide and iron.

Blast furnace: The iron is removed from its ore Fe₂O₃, which is used to make steel, in a blast furnace. Carbon replaces Ferrous in the process, resulting in carbon dioxide. The reaction is:

$3 \mathrm{C}+2 \mathrm{Fe}_2 \mathrm{O}_3 \rightarrow 3 \mathrm{CO}_2+4 \mathrm{Fe}$

Carbon displaces the iron from the iron oxide forming carbon dioxide and iron.

Metal extraction: Metals are formed by heating metal combinations in the presence of carbon. When a Cr₂O₃ combination is heated, chromium is produced. The reaction will be:

$3 \mathrm{C}+2 \mathrm{Cr}_2 \mathrm{O}_3 \rightarrow 3 \mathrm{CO}_2+4 \mathrm{Cr}$

Displacement Reaction Examples

Single displacement reaction examples –

• Displacement of copper from copper sulphate –

$\mathrm{Zn}+\mathrm{CuSO}_4 \rightarrow \mathrm{ZnSO}_4+\mathrm{Cu}$

• Displacement of silver from silver nitrate –

$\mathrm{Cu}+2 \mathrm{AgNO}_3 \rightarrow \mathrm{CuNO}_3+2 \mathrm{Ag}$

• Displacement of copper from copper sulphate –

$\mathrm{Fe}+\mathrm{CuSO}_4 \rightarrow \mathrm{Cu}+\mathrm{FeSO}_4$

• Displacement of copper from copper chloride –

$\mathrm{Pb}+\mathrm{CuCl}_2 \rightarrow \mathrm{Cu}+\mathrm{PbCl}_2$

• Displacement of sodium from sodium bromide –

$\mathrm{Cl}_2+2 \mathrm{NaBr} \rightarrow 2 \mathrm{NaCl}+\mathrm{Br}_2$

Double displacement reaction examples -

• Displacement of aluminum from aluminum trichloride and potassium from potassium chloride –

$\mathrm{KNO}_3+\mathrm{AlCl}_3 \rightarrow \mathrm{Al}\left(\mathrm{NO}_3\right)_3+\mathrm{KCl}$

• Displacement of lead from lead nitrate and potassium from potassium iodide –

$\mathrm{Pb}\left(\mathrm{NO}_3\right)_2+2 \mathrm{KI} \rightarrow 2 \mathrm{KNO}_3+\mathrm{PbI}_2$

• Displacement of barium from barium hydroxide and iron from iron chloride –

$\mathrm{FeCl}_3+\mathrm{Ba}(\mathrm{OH})_2 \rightarrow \mathrm{Fe}(\mathrm{OH})_2+\mathrm{BaCl}_2$

• Displacement of sodium from sodium sulphate and lead from lead nitrate –

$\mathrm{Pb}\left(\mathrm{NO}_3\right)_2+\mathrm{Na}_2 \mathrm{SO}_4 \rightarrow \mathrm{PbSO}_4+2 \mathrm{NaNO}_3$

• Displacement of barium from barium chloride and copper from copper sulphate –

$\mathrm{BaCl}_2+\mathrm{CuSO}_4 \rightarrow \mathrm{BaSO}_4+\mathrm{CuCl}_2$

Also read -

Some Solved Examples

Question 1: Match the following reactions to their types:

1. $2 \mathrm{AgBr} \xrightarrow{\text { sunlight }} 2 \mathrm{Ag}+\mathrm{Br}_2$ p. Combination reaction

2.$3 \mathrm{MnO}_4^{2-}+4 \mathrm{H}^{+} \rightarrow 2 \mathrm{MnO}_4^{-}+\mathrm{MnO}_2$ q. Disproportionation reaction

3.$2 \mathrm{Na}+\frac{1}{2} \mathrm{O}_2 \rightarrow \mathrm{Na}_2 \mathrm{O}+2 \mathrm{H}_2 \mathrm{O}$ r. Decomposition reaction

4.$\mathrm{CuSO}_4+\mathrm{Zn} \rightarrow \mathrm{ZnSO}_4+\mathrm{CuS}$ s. Non-metal displacement reaction

1) (correct) $1-r, 2-q, 3-p, 4-s$

2) 1-q,2-s,3-p,4-r
3) 1-q,2-p,3-s,4-r
4) 1-s,2-q,3-p,4-r

Solution:

As we learnt

Decomposition Reaction -

This is opposite of combination reaction precisely, a decomposition reaction lead to the breakdown of a compound into two or more components at least one of which must be in an elemental state.

- wherein

$2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \stackrel{\Delta}{\rightarrow} 2 \mathrm{H}_2(g)+\mathrm{O}_2(g)$

+1 -2 0 0

$2 \mathrm{AgBr} \xrightarrow{\text { sunlight }} 2 \mathrm{Ag}+\mathrm{Br}_2$ is a decomposition reaction.

Hence, the answer is the option (1).

Question 2: Which of the following is non metal displacement Redox Reaction.
1) $\mathrm{Mg}+2 \mathrm{HCl} \rightarrow \mathrm{MgCl}_2+\mathrm{H}_2$

2) $2 \mathrm{H}_2 \mathrm{O}+2 \mathrm{~F}_2 \rightarrow 4 \mathrm{HF}+\mathrm{O}_2$

3) $\mathrm{Cl}_2+2 \mathrm{KI} \rightarrow 2 \mathrm{KI}+\mathrm{I}_2$

4) (correct) All of these

Solution:

As we learned

Non-metal Displacement -

The non-metal displacement redox reaction includes hydrogen displacement and a rarely occurring reaction involving oxygen displacement.

- wherein

$2 \mathrm{Na}(\mathrm{s})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightarrow 2 \mathrm{NaOH}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})$

0 +1 -2 1 -2 +1 0

Given all non-metals are displacement Redox reaction.

Hence, the answer is the option (4).

Question 3: Which of the following is Metal displacement Redox Reaction.
1) $2 \mathrm{Na}+2 \mathrm{H}_2 \mathrm{O} \rightarrow 2 \mathrm{NaOH}+\mathrm{H}_2$

2) (correct) $\mathrm{CuSO}_4+\mathrm{Zn} \rightarrow \mathrm{ZnSO}_4+\mathrm{Cu}$
3) $\mathrm{Cl}_2+2 \mathrm{OH}^{-} \rightarrow \mathrm{ClO}^{-}+\mathrm{Cl}^{-}+\mathrm{H}_2 \mathrm{O}$

4) $3 M g+N_2 \rightarrow M g_3 N_2$

Solution:

As we learned

Metal Displacement Reaction -

A metal in a compound can be displaced by another metal in the uncombined. It has much application in metallurgical processes.

- wherein

$V_2 \mathrm{O}_5(\mathrm{~s})+5 \mathrm{Ca}(\mathrm{s}) \xrightarrow{\Delta} 2 \mathrm{~V}(\mathrm{~s})+5 \mathrm{Ca} \mathrm{O}(\mathrm{s})$

+5 -2 0 0 +2 -2

Metal displacement Redox Reaction is

$\mathrm{CuSO}_4+\mathrm{Zn} \rightarrow \mathrm{ZnSO}_4+\mathrm{Cu}$

Hence, the answer is the option (2).

Question 4: In which of the following cases a chemical reaction is possible?
1) (correct) $\mathrm{AgNO}_3$ solution is stirred with a copper spoon
2) Conc. $\mathrm{HNO}_3$ is stored in a platinum vessel
3) gold ornaments are washed with dil HCl
4) $\mathrm{ZnSO4}(\mathrm{aq})$ is placed in a copper vessel

Solution:

When AgNO₃ solution is stirred with a copper spoon, displacement reaction will take place which will form a new compound called as copper nitrate.

In all other cases no chemical reaction takes place between the components taken.

Hence only option in which chemical reaction is possible is when AgNO₃ solution is stirred with a copper spoon

Hence, the answer is the option (1).

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