Problem 138 - A Complete Resource Book in Chemistry for JEE Main

Question

Which are correct statements for \(\mathrm{XeF}_{2} ?\) (a) it oxidizes \(\mathrm{Cl}^{-}\)and \(\mathrm{I}^{-}\)to \(\mathrm{Cl}_{2}\) and \(\mathrm{I}_{2}\) respectively (b) it has linear structure (c) it cannot act as \(\mathrm{F}\) - donor (d) it is hydrolyzed rapidly in aqueous solution of a base (a) 1,2 and 4 (b) 1,3 and 4 (c) 2,3 and 4 (d) 3 and 4 only

Step-by-Step Solution

Answer

Correct statements are 2 and 4 (option d).

Step 1: Consider the Oxidizing Ability

The first statement claims that \( \text{XeF}_2 \) can oxidize \( \text{Cl}^- \) and \( \text{I}^- \) to form \( \text{Cl}_2 \) and \( \text{I}_2 \) respectively. \( \text{XeF}_2 \) is a strong fluorinating agent and an oxidizer, often used to oxidize significant halides like \( \text{I}^- \), but not typically \( \text{Cl}^- \) because \( \text{XeF}_2 \) itself might become reduced in such processes. Thus, this statement is partially correct for \( \text{I}^- \) but not typically for \( \text{Cl}^- \).

Step 2: Analyze the Molecular Structure

The second statement claims that \( \text{XeF}_2 \) has a linear structure. Xenon difluoride has a linear configuration due to the symmetrical distribution of lone pairs around xenon causing the fluorine atoms to align opposite each other. This aligns with the valence shell electron pair repulsion theory (VSEPR), which supports the linear structure.

Step 3: Examine Fluorine Donor Ability

The third statement advises that \( \text{XeF}_2 \) cannot act as a fluorine donor. \( \text{XeF}_2 \) acts more commonly as a source of fluorine in reactions, fluorinating other species, which means in most cases, it can actually act as a fluorine donor.

Step 4: Evaluate Reaction in Basic Aqueous Solutions

The fourth statement implies that \( \text{XeF}_2 \) is rapidly hydrolyzed in a basic aqueous solution. \( \text{XeF}_2 \) does undergo hydrolysis in basic solutions, leading it to decompose, showing that this statement is correct.

Key Concepts

Oxidizing Ability

One of the fascinating properties of xenon difluoride (\(\text{XeF}_2\)) is its role as an oxidizing agent. In particular, it is known for its ability to oxidize iodide ions (\(\text{I}^-\)) into iodine (\(\text{I}_2\)). However, \(\text{XeF}_2\) does not typically oxidize chloride ions (\(\text{Cl}^-\)) into chlorine (\(\text{Cl}_2\)). This specificity arises because \(\text{XeF}_2\) itself can be reduced during these reacting processes, but preferences in chemical reactivity favor the exchange with iodide.

• \(\text{XeF}_2\) is a well-regarded fluorinating agent.
• It acts as an oxidizer primarily for iodine species.
• It plays a less significant role with chlorine species.

The strength of \(\text{XeF}_2\) as an oxidizing agent is leveraged in many chemical applications where the goal is to transform halide ions.

Molecular Structure

The molecular structure of \(\text{XeF}_2\) is particularly interesting due to its simplicity and symmetry. \(\text{XeF}_2\) has a linear configuration, which can be understood through the valence shell electron pair repulsion (VSEPR) theory. According to VSEPR, the bonds of \(\text{XeF}_2\) arrange in such a way as to minimize repulsion between the electron pairs.

• \(\text{XeF}_2\) has one xenon atom flanked by two fluorine atoms.
• This arrangement leads to a straight, 180-degree linear structure.

The linear structure arises from the symmetric distribution of lone pairs around xenon, causing the terminal fluorine atoms to align uniformly, which is a hallmark example of how electron-electron repulsion shapes molecular configuration.

Fluorine Donor

A significant property of \(\text{XeF}_2\) is its functionality as a fluorine donor. Though sometimes mistakenly believed to be unable to donate fluorine, \(\text{XeF}_2\) is indeed a well-known source of fluorine in various chemical reactions. Its ability to transfer fluorine atoms makes it invaluable in synthesizing and modifying chemical compounds.

• \(\text{XeF}_2\) is utilized in organic and inorganic chemistry to impart fluoride ions.
• It actively participates in fluorination reactions where it donates fluorine atoms to substrates.

Thus, \(\text{XeF}_2\) is effectively engaged in reactions as a fluorine source, contributing significantly to chemical synthesis.

Hydrolysis in Basic Solution

When dissolved in a basic solution, \(\text{XeF}_2\) is susceptible to rapid hydrolysis. Hydrolysis is a chemical reaction involving the breakdown of a compound due to its reaction with water. In basic conditions, \(\text{XeF}_2\) decomposes more readily compared to neutral or acidic environments.

• Basic solutions increase the rate of hydrolysis for \(\text{XeF}_2\).
• This reaction leads to the generation of various oxidation products.

Understanding the behavior of \(\text{XeF}_2\) in different environments is crucial for its safe and effective use in practical and industrial applications.