Question

Which of the following reacts readily with \(\mathrm{SiO}_{2}\) to give \(\mathrm{SiF}_{4}\) ? (a) \(\mathrm{C}_{2} \mathrm{~F}_{6}\) (b) \(\mathrm{XeF}_{6}\) (c) \(\mathrm{CaF}_{2}\) (d) \(\mathrm{NaF}\)

Short answer

(b) \( \mathrm{XeF}_{6} \)

Step-by-step solution

Understand the Reaction

The problem asks which compound reacts readily with \( \mathrm{SiO}_{2} \) to produce \( \mathrm{SiF}_{4} \). This implies a reaction of the form: \( \mathrm{SiO}_{2} + X \rightarrow \mathrm{SiF}_{4} + \text{other products} \). Our task is to identify the correct fluorine-containing reactant (X) from the options given.

Analyze Options

Consider the properties of each compound:- (a) \( \mathrm{C}_{2} \mathrm{~F}_{6} \): This compound is a stable perfluorocarbon and unlikely to fluorinate \( \mathrm{SiO}_{2} \).- (b) \( \mathrm{XeF}_{6} \): Known for being highly reactive, especially as a fluorination agent.- (c) \( \mathrm{CaF}_{2} \): Requires high temperatures to provide fluoride ions.- (d) \( \mathrm{NaF} \): Reacts with \( \mathrm{SiO}_{2} \) at high temperatures, but less reactive compared to \( \mathrm{XeF}_{6} \).

Evaluate Reactivity

\( \mathrm{XeF}_{6} \) is a strong fluorinating agent, making it highly suitable for generating \( \mathrm{SiF}_{4} \) from \( \mathrm{SiO}_{2} \) due to its ability to easily transfer fluorine atoms. The other options either do not react readily with \( \mathrm{SiO}_{2} \) or require more extreme conditions to do so.

Conclusion

Given \( \mathrm{XeF}_{6} \)'s known reactivity and its role as a fluorine donor, it is the best candidate for reacting with \( \mathrm{SiO}_{2} \) to produce \( \mathrm{SiF}_{4} \) readily.

Key concepts

Silicon Dioxide (SiO2)

Silicon dioxide, commonly referred to as silica, is a pivotal compound in both chemistry and the natural world. It is naturally found in materials like sand and quartz and exhibits a strong and stable structure due to its covalent bonding between silicon and oxygen atoms.

• Silicon, the central atom, is bonded to four oxygen atoms in a tetrahedral arrangement.
• This arrangement gives SiO₂ its notable hardness and chemical inertness.

Silicon dioxide plays an essential role in glass manufacturing as well as the construction of certain electronic components due to its insulating properties. In chemistry, despite its stability, SiO₂ can serve as a starting material or reactant in specific high-energy reactions, such as those producing silicon tetrafluoride (\(\mathrm{SiF}_{4}\)). Studying these reactions involving SiO₂ helps us understand both its reactivity and utility in chemical synthesis.

Fluorination

Fluorination is a chemical process where a fluorine atom is introduced into a molecule. It modifies the chemical and physical properties of compounds, often enhancing their stability and reactivity due to the high electronegativity of fluorine.
This process can be critical in organic and inorganic chemistry for:

• Producing fluorocarbons that are valuable in different industrial applications.
• Creating compounds like hydrogen fluoride and other fluorides.

Inorganic fluorination often utilizes reactive agents like \(\mathrm{XeF}_{6}\) due to their ability to transfer fluorine atoms efficiently. Compounds produced through fluorination, such as \(\mathrm{SiF}_{4}\), demonstrate significant changes in reactivity compared to their non-fluorinated counterparts.

Reactivity of Xenon Compounds

Xenon compounds, especially xenon fluorides, are renowned for their remarkable reactivity, even though xenon is a noble gas and traditionally viewed as non-reactive. These compounds, like \(\mathrm{XeF}_{6}\), react vigorously with a variety of substances due to xenon's ability to form stable bonds with highly electronegative elements like fluorine.
Consider the following about \(\mathrm{XeF}_{6}\):

• It acts as a potent fluorinating agent.
• It can readily donate fluorine atoms in chemical reactions.

In reactions involving \(\mathrm{SiO}_{2}\), \(\mathrm{XeF}_{6}\) efficiently transfers fluorine to silicon, resulting in the formation of \(\mathrm{SiF}_{4}\). This interaction highlights the reactivity of xenon compounds and their application in creating other compounds through the direct transfer of fluorine atoms.