Problem 77 - A Complete Resource Book in Chemistry for JEE Main

Question

Fluorine is obtained by the interaction of \(\mathrm{K}_{2} \mathrm{MnF}_{6}\) with Lewis acid \(\mathrm{SbF}_{5}\) because of the (a) acidalysis of \(\mathrm{MnF}_{4}\) (b) ionization of \(\mathrm{MnF}_{4}\) (c) decomposition of \(\mathrm{SbF}_{6}\) (d) decomposition of \(\mathrm{MnF}_{4}\)

Step-by-Step Solution

Answer

Fluorine is obtained by the decomposition of \(\mathrm{MnF}_{4}\).

Step 1: Understand the problem

The problem asks us to identify how fluorine is obtained from the reaction between \(\mathrm{K}_{2} \mathrm{MnF}_{6}\) and \(\mathrm{SbF}_{5}\). We need to consider the chemical processes involved.

Step 2: Investigate the interaction

\(\mathrm{K}_{2} \mathrm{MnF}_{6}\) is composed of \(\mathrm{MnF}_{4}\) and fluorine ions. When it reacts with \(\mathrm{SbF}_{5}\), the acid acts as a fluorine acceptor, facilitating the process that leads to the liberation of fluorine gas.

Step 3: Analyze possible processes

The options given are different types of processes: acidalysis, ionization, and decomposition. Given the presence of \(\mathrm{MnF}_{4}\), likely chemical activity includes breakdown or decomposition since fluorine gas needs to be released.

Step 4: Identify the correct option

In such reaction with \(\mathrm{SbF}_{5}\), the most likely process is the decomposition of \(\mathrm{MnF}_{4}\), where \(\mathrm{MnF}_{4}\) breaks down, leading to the release of fluorine gas.

Key Concepts

Lewis Acids

In chemistry, Lewis acids play a vital role as they are substances that can accept an electron pair. This unique ability makes them crucial in a variety of chemical reactions, including those involving the release of gases like fluorine. Lewis acids are named after Gilbert N. Lewis, who first proposed the concept.

### Characteristics of Lewis Acids
Lewis acids often possess an incomplete octet of electrons, which means they have empty orbitals available to accept electron pairs. Examples include many metal cations and molecules like boron trifluoride (BF₃) or antimony pentafluoride (SbF₅).

When a Lewis acid reacts with a compound that has electron pairs available to be donated, like \(mathrm{K}_{2} /mathrm{MnF}_{6}\), it facilitates the release or transformation of certain molecules. In this scenario, the SbF₅ acts by binding to fluorine ions, which helps in the decomposition process, eventually leading to the liberation of fluorine gas.

This concept is especially useful in industrial and laboratory processes where specific reactions are desired to produce or manipulate certain chemicals.

Decomposition Reaction

A decomposition reaction involves the breakdown of a single compound into two or more simpler substances. This type of reaction is fundamental in chemistry and often requires energy, like heat or light, to occur. In the preparation of fluorine, decomposition reactions are essential.

### Example in Fluorine Preparation
When \(\mathrm{K}_{2} \mathrm{MnF}_{6}\) interacts with the Lewis acid \(\mathrm{SbF}_{5}\), a decomposition reaction occurs. Here, \(\mathrm{MnF}_{4}\) breaks down primarily due to the electron-pair accepting nature of \(\mathrm{SbF}_{5}\). This leads to the production of fluorine gas, as \(\mathrm{MnF}_{4}\) decomposes and releases fluorine ions.

This process exemplifies how decomposition reactions can be driven by external agents like Lewis acids, which facilitate the breakdown of complex molecules. Such interactions are crucial in chemical industries and laboratories where controlled reactions need to be carried out to produce specific chemicals or elements.

Potassium Hexafluoromanganate(IV)

Potassium hexafluoromanganate(IV), denoted as \(\mathrm{K}_{2} \mathrm{MnF}_{6}\), is a compound that features prominently in the production of fluorine gas. To better understand its role, it's useful to explore its structure and reactivity.

### Structure and Composition
This compound consists of potassium ions (K⁺) and the hexafluoromanganate(IV) complex, \(\mathrm{MnF}_{6}^{2-}\). Within this, manganese is surrounded by six fluoride ions. The structure is held together by ionic bonds, with the fluoride ions offering electron pairs that can be accepted by Lewis acids.

### Role in Fluorine Production
When involved in reactions with Lewis acids like \(\mathrm{SbF}_{5}\), the complex undergoes a chemical process where manganese tetrafluoride, \(\mathrm{MnF}_{4}\), decomposes. This breakdown releases fluorine gas into the environment. The role of \(\mathrm{K}_{2} \mathrm{MnF}_{6}\) is crucial as it is an effective fluorine source due to its ability to easily undergo decomposition in the presence of certain catalysts or agents, such as Lewis acids.

Overall, its role in industry is pivotal as it offers a feasible path to produce fluorine through controlled decomposition, making it invaluable for applications requiring this highly reactive element.