Problem 212 - A Complete Resource Book in Chemistry for JEE Main

Question

Which one of the following reactions of Xenon compound is not feasible? [2009] (a) \(3 \mathrm{XeF}_{4}+6 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{Xe}+\mathrm{XeO}_{3}+12 \mathrm{HF}+1.5 \mathrm{O}_{2}\) (b) \(2 \mathrm{XeF}_{2}+2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{Xe}+4 \mathrm{HF}+\mathrm{O}_{2}\) (c) \(\mathrm{XeF}_{6}+\mathrm{RbF} \longrightarrow \mathrm{Rb}\left[\mathrm{XeF}_{7}\right]\) (d) \(\mathrm{XeO}_{3}+6 \mathrm{HF} \longrightarrow \mathrm{XeF}_{6}+3 \mathrm{H}_{2} \mathrm{O}\)

Step-by-Step Solution

Answer

Reaction (d) is not feasible.

Step 1: Analyze Reaction (a)

In reaction (a), XeF4 is reacting with water to form Xe, XeO3, HF, and O2. This is a redox reaction where Xenon is being reduced and also forming a stable oxide (XeO3), which is feasible under certain conditions. Thus, this reaction can occur.

Step 2: Analyze Reaction (b)

Reaction (b) involves XeF2 reacting with water to produce Xe, HF, and O2. This is a feasible reaction as XeF2 is known to react with water, decomposing to xenon, oxygen, and hydrogen fluoride. This reaction is likely to occur.

Step 3: Analyze Reaction (c)

In reaction (c), XeF6 reacts with RbF to form a complex XeF7^- ion, a plausible reaction because RbF can donate F^- to form the heptafluoroxenate anion, \([\mathrm{XeF}_{7}]^-\). This reaction is feasible.

Step 4: Analyze Reaction (d)

Reaction (d) involves XeO3 reacting with HF to produce XeF6 and water. XeO3 is a stable compound and converting it directly to XeF6 via HF is not known to be feasible. Converting an oxide to a fluoride typically requires intermediate steps or conditions that vary greatly, making this reaction not feasible.

Step 5: Conclusion

From our analysis of each reaction, reaction (d) is the only one that lacks feasibility based on the stability and typical reactions of Xenon oxides with acids, and lack of known direct conversion from XeO3 to XeF6 using HF.

Key Concepts

Redox Reactions

Redox reactions, short for reduction-oxidation reactions, are processes where electrons are transferred between two substances. In these reactions, one reactant undergoes oxidation where it loses electrons and another undergoes reduction where it gains electrons.
Understanding redox reactions is crucial to comprehend how xenon compounds like xenon fluoride participate in chemical processes. Here’s a simple way to think of them:

• Oxidation involves the loss of electrons.
• Reduction involves the gain of electrons.
• A substance that donates electrons is called a reducing agent.
• A substance that accepts electrons is called an oxidizing agent.

In the context of xenon compounds, xenon acts as a central atom, interacting with various elements. A classic example is the reaction between xenon tetrafluoride (\( \text{XeF}_4 \)) and water, forming xenon trioxide (\( \text{XeO}_3 \)) along with xenon and oxygen gases. This transformation exemplifies a redox process driven by significant electron transfer between xenon and the other reacting substances.

Xenon Fluoride

Xenon fluoride compounds are intriguing examples of noble gas chemistry. Historically, noble gases were considered non-reactive due to their complete valence electron shells. However, xenon can form stable fluoride compounds like \( \text{XeF}_2 \), \( \text{XeF}_4 \), and \( \text{XeF}_6 \) due to its ability to hold additional electrons in higher energy orbitals.
These compounds are known for their strong oxidizing properties, allowing them to engage in a multitude of reactions. For instance:

• \( \text{XeF}_2 \) is a powerful oxidizing agent, reacting swiftly with water to produce xenon gas, hydrogen fluoride (\( \text{HF} \)), and oxygen.
• \( \text{XeF}_4 \) can also split into xenon, water, hydrofluoric acid, and oxygen when it reacts with water.

The versatility of xenon fluoride compounds highlights their importance in synthetic chemistry and their role in exploring the boundaries of chemical reactivity.

Xenon Oxides

Xenon oxides are a lesser-known but fascinating part of xenon's chemistry, illustrating its ability to bond with oxygen. The most common oxide, xenon trioxide (\( \text{XeO}_3 \)), is a highly unstable and explosive compound with impressive oxidizing capabilities.
Here are a few key insights about xenon oxides:

• \( \text{XeO}_3 \) is produced during the hydrolysis of xenon compounds in the presence of water.
• Reactions involving xenon oxides are generally complex and need precise conditions to achieve desired products.
• Xenon oxides are notable for their role in advancing the study of oxidation reactions involving noble gases.

In contrast to xenon fluorides, directly transforming xenon trioxide to other xenon compounds like \( \text{XeF}_6 \) is not straightforward, often requiring intermediate processes or conditions unlikely to occur naturally.

Reaction Feasibility

Understanding the feasibility of chemical reactions involves evaluating the conditions and likelihood under which a reaction occurs. This includes examining thermodynamics, kinetics, and existing knowledge of chemical behavior.
Steps to evaluate feasibility include:

• Assessing energy changes: Reactions that release energy (exothermic) are more likely to occur naturally.
• Identifying stable vs. reactive intermediates: Predicting whether reactants will persist or convert into more stable products.
• Observing past experimental data and known chemical principles.

For xenon compounds, feasibility is influenced by their oxidizing potential and bonding preferences. In the given examples, the transformation of \( \text{XeO}_3 \) directly into \( \text{XeF}_6 \) is deemed infeasible without intermediate steps, given \( \text{XeO}_3 \)'s stability. Meanwhile, reactions involving water and xenon fluorides tend to be feasible due to the energetic favorability and chemical behavior known from research and historical data.