Question

Explain the difference between a single-displacement reaction and a double- displacement reaction and provide an example of each.

Short answer

A single-displacement reaction involves one element replacing another in a compound, like Zn reacting with HCl to produce ZnCl2 and H2. A double-displacement reaction involves two compounds exchanging components, such as NaCl reacting with AgNO3 to produce NaNO3 and AgCl.

Step-by-step solution

Identify the Single-Displacement Reaction

A single-displacement reaction, also known as a substitution reaction, occurs when one element trades places with another element in a compound, forming a new element and a new compound. It generally follows the form: A + BC -> AC + B, where A is a single element that replaces B in the compound BC.

Provide an Example of a Single-Displacement Reaction

An example of a single-displacement reaction is when zinc metal is placed in a solution of hydrochloric acid (HCl). Zinc displaces the hydrogen to form zinc chloride (ZnCl2) and hydrogen gas (H2). The reaction can be represented by the equation: Zn + 2HCl -> ZnCl2 + H2.

Identify the Double-Displacement Reaction

A double-displacement reaction, also known as a metathesis reaction, involves the exchange of parts between two compounds to form two new compounds. It typically follows the form: AB + CD -> AD + CB, where AB and CD are compounds that exchange their partners to form new compounds AD and CB.

Provide an Example of a Double-Displacement Reaction

An example of a double-displacement reaction is the reaction between sodium chloride (NaCl) and silver nitrate (AgNO3). When these compounds react, the sodium trades places with the silver, and the chloride trades places with the nitrate, forming sodium nitrate (NaNO3) and silver chloride (AgCl). The reaction can be written as: NaCl + AgNO3 -> NaNO3 + AgCl.

Key concepts

Single-Displacement Reaction

In the fascinating world of chemistry, a single-displacement reaction stands out with its simple yet vital role in various processes. Imagine a dance where a person (element A) cuts in and takes the place of one of the partners (element B) in a duo (compound BC), leaving the ousted partner to stand alone. In chemical terms, this occurs when an element A displaces and replaces another element B in a compound, resulting in a new compound AC and the freed element B.

The equation that typically represents this type of reaction is: \[ A + BC \rightarrow AC + B \] For instance, if we take zinc (Zn) and introduce it to hydrochloric acid (HCl), a reaction ensues. Zinc usurps the place of hydrogen in the compound, leading to the formation of zinc chloride (ZnCl2) and hydrogen gas (H2) as a by-product. This is represented by the chemical equation: \[ Zn + 2HCl \rightarrow ZnCl2 + H2 \] This example demonstrates a classic single-displacement reaction involving metals and acids, often observed in corrosion and battery processes.

Double-Displacement Reaction

Taking the complexity a step further, the double-displacement reaction is like a dance where two couples decide to swap partners. This type of reaction occurs between ions in two different compounds that exchange partners, forming two new compounds. It's a grand molecular waltz where compound AB waltzes with CD, resulting in the new pairings of AD and CB.

The general form for this reaction is presented as: \[ AB + CD \rightarrow AD + CB \] A prime example of this reaction is observed when we mix a solution of sodium chloride (NaCl) with silver nitrate (AgNO3). In this reaction, sodium (Na) pairs up with nitrate (NO3), and silver (Ag) joins forces with chloride (Cl), forming sodium nitrate (NaNO3) and silver chloride (AgCl). The full equation comes out as: \[ NaCl + AgNO3 \rightarrow NaNO3 + AgCl \] This reaction not only illustrates the concept but also has practical applications in various fields including photography, where silver chloride plays a crucial role.

Chemical Reaction Examples

Chemical reactions are the backbone of both natural processes and industrial applications. To cement your understanding, let's consider a few more examples.

• Combustion: A reaction where a substance combines with oxygen, often producing heat and light, as in the burning of natural gas: \( CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O \).
• Synthesis: When multiple reactants combine to form a single product, like the formation of water: \( 2H_2 + O_2 \rightarrow 2H_2O \).
• Decomposition: A single compound breaks down into two or more products, such as the breakdown of potassium chlorate when heated: \( 2KClO_3 \rightarrow 2KCl + 3O_2 \).

These examples span the range from the simplicity of synthesis reactions to the complexity of decomposition, each showcasing the fascinating transformations that substances can undergo.

Reaction Mechanisms

The reaction mechanism is the detailed step-by-step description of how a reaction occurs at the molecular level. It's the behind-the-scenes look at the actors (molecules) and their roles in the microscopic theater of a chemical reaction. Reaction mechanisms involve bond breaking and bond forming and are often depicted using arrows to show the movement of electrons during the reaction process.

For instance, in the single-displacement reaction of zinc and hydrochloric acid, the mechanism involves zinc atoms donating electrons to hydrogen ions, thus freeing them as hydrogen gas while forming zinc ions that combine with chloride ions to produce zinc chloride.

Understanding the mechanism provides insights into reaction kinetics, the speed of a reaction, and catalysts' roles. It is knowledge of these intimate details that allows chemists to predict and manipulate chemical reactions for various practical applications, including drug development and the synthesis of new materials.