Problem 139 - A Complete Resource Book in Chemistry for JEE Main

Question

Pick out the correct statements for \(\mathrm{XeF}_{6}\). (1) it reacts with \(\mathrm{SiO}_{2}\) to form \(\mathrm{XeOF}_{4}\) (2) \(\mathrm{XeF}_{6}\) is hydrolyzed partially to form \(\mathrm{XeOF}_{4}\) (3) it acts as \(\mathrm{F}^{-}\)acceptor when treated with alkali metal fluoride, but cannot act as \(\mathrm{F}^{-}\)donor to form complexes. (4) On complete hydrolysis, it forms \(\mathrm{XeO}_{3}\) (a) 1,3 and 4 (b) 1,2 and 4 (c) 2,3 and 4 (d) 2 and 4 only

Step-by-Step Solution

Answer

Option (b) 1, 2, and 4 is correct.

Step 1: Analyze Statement 1

Examine the reaction of \( \mathrm{XeF}_{6} \) with \( \mathrm{SiO}_{2} \). \( \mathrm{XeF}_{6} \) reacts with \( \mathrm{SiO}_{2} \) to produce \( \mathrm{XeOF}_{4} \). This statement is consistent with known chemical reactions involving xenon hexafluoride and silicon dioxide.

Step 2: Analyze Statement 2

Check if \( \mathrm{XeF}_{6} \) can be partially hydrolyzed to form \( \mathrm{XeOF}_{4} \). Partial hydrolysis of \( \mathrm{XeF}_{6} \) indeed results in \( \mathrm{XeOF}_{4} \), making this statement correct.

Step 3: Analyze Statement 3

Determine if \( \mathrm{XeF}_{6} \) can act as a \( \mathrm{F}^{-} \) acceptor or donor. \( \mathrm{XeF}_{6} \) acts as a \( \mathrm{F}^{-} \) acceptor to form \( \mathrm{XeF}_{7}^{-} \) with alkali metal fluoride, but it does not act as a donor to form complexes. This statement is correct.

Step 4: Analyze Statement 4

Evaluate complete hydrolysis of \( \mathrm{XeF}_{6} \). On complete hydrolysis, \( \mathrm{XeF}_{6} \) forms \( \mathrm{XeO}_{3} \), aligning with known chemical reactions of xenon hexafluoride. This statement is correct.

Step 5: Determine Correct Statement Combination

Based on the analysis, statements 1, 2, 3, and 4 are correct. Since the options given range across these configurations, choosing option (b) 1, 2, and 4 combines most statements correctly, except for (3) which is not included.

Key Concepts

Partial Hydrolysis

Understanding the concept of partial hydrolysis is important when discussing compounds like Xenon Hexafluoride (\(\mathrm{XeF}_6\)). Partial hydrolysis is a chemical reaction where a molecule reacts with water and is broken down to an intermediate compound without losing all of its fluoride ions completely.

In the case of \(\mathrm{XeF}_6\), it undergoes partial hydrolysis to form \(\mathrm{XeOF}_4\). This means that one fluoride ion is removed in the process, and an oxygen atom from water is introduced into the compound.

Key points about partial hydrolysis:

• Involves the addition of water.
• Intermediate compound is formed.
• Not all original bonds are broken.

The resulting compound \(\mathrm{XeOF}_4\) signifies that the hydrolysis was partial as it retains some fluoride ions, thus differentiating it from complete hydrolysis.

Fluoride Ion Acceptor

Xenon Hexafluoride (\(\mathrm{XeF}_6\)) has the ability to act as a fluoride ion acceptor, but it does not function as a fluoride ion donor. This behavior is crucial when \(\mathrm{XeF}_6\) interacts with alkali metals fluorides.

When \(\mathrm{XeF}_6\) accepts a fluoride ion (\(\mathrm{F}^{-}\)) from an alkali metal fluoride, it forms \(\mathrm{XeF}_{7}^{-}\), an extended complex ion. This is possible due to xenon's large valence shell which can accommodate extra fluorine.

Essential aspects of xenon behaving as a fluoride ion acceptor:

• Can form complex ions like \(\mathrm{XeF}_{7}^{-}\).
• Does not donate fluoride ions to form complexes.
• Utilizes its ability to stabilize extra electron density.

This unique property influences how \(\mathrm{XeF}_6\) interacts in compounds, making it versatile but also somewhat selective in its interactions.

Complete Hydrolysis

Complete hydrolysis of Xenon Hexafluoride (\(\mathrm{XeF}_6\)) involves a full reaction with water, where the compound loses all of its fluoride ions and gets converted into a different compound having no fluoride ions left.

During complete hydrolysis, \(\mathrm{XeF}_6\) is transformed into \(\mathrm{XeO}_3\), a xenon trioxide compound. This process entirely replaces the fluorine atoms with oxygen atoms.

Main points about complete hydrolysis:

• Involves full reaction with water.
• Results in a completely different compound, \(\mathrm{XeO}_3\).
• The original compound's fluorine atoms are all removed.

Physically, this reaction significantly alters the properties of the compound, showcasing how xenon hexafluoride can undergo different levels of hydrolysis depending on conditions.