Question

KF combines with HF to form \(\mathrm{KHF}_{2}\). The compound contains the species (a) \(\mathrm{K}^{+}, \mathrm{F}^{-}\) and \(\mathrm{H}^{+}\) (b) \(\mathrm{K}^{+}, \mathrm{F}^{-}\) and \(\mathrm{HF}\) (c) \(\mathrm{K}^{+}\) and \(\left[\mathrm{HF}_{2}\right]\) (d) \([\mathrm{KHF}]^{+}\) and \(\mathrm{F}_{2}\)

Short answer

The compound contains \(\mathrm{K^+}\) and \([\mathrm{HF}_2]^-.\) (Option c)

Step-by-step solution

Understanding the Reaction of KF with HF

KF is composed of potassium (K) and fluoride (F) ions, and HF is hydrogen fluoride. When these two react, they form potassium hydrogen difluoride (0AA)0A. Our task is to understand the ionic composition of 0AA).

Identifying Potential Ionic Components

In the compound 0AA), potassium typically forms 0AA) ions, fluorine forms 0AA) ions, and hydrogen can be part of the bifluoride ion 0AA) .). This bifluoride ion is a stable ion where a hydrogen ion is shared between two fluoride ions.

Mapping to the Given Options

Let's now compare with the possible ionic structures given in the options: - (a) lists each ion separately but does not consider the bifluoride structure. - (b) incorrectly maintains HF as a molecule, which is less stable than the bifluoride ion. - (c) correctly pairs 0AA) with the bifluoride ion 0AA) suggesting the stable ionic form consistent with known chemistry. - (d) implies concentrated molecular species that do not align with known chemistry.

Selecting the Correct Component Option

From Step 3, option (c) depicting 0AA) and 0AA) is correct. This choice reflects the ionic state of the compound 0AA previously described.

Key concepts

Potassium Hydrogen Difluoride

Potassium Hydrogen Difluoride, often denoted as \( \text{KHF}_2 \), is an interesting compound formed by the reaction of potassium fluoride \( (\text{KF}) \) and hydrogen fluoride \( (\text{HF}) \). It is widely recognized in inorganic chemistry due to its unique composition and structure. In this compound, potassium (K) pairs with a unique combination of hydrogen and fluoride ions. This results in the formation of the stable bifluoride ion, which is less common compared to the more straightforward ionic pairings. Rather than existing as separate fluoride \( (\text{F}^-) \) and hydrogen \( (\text{H}^+) \) ions, in \( \text{KHF}_2 \), these constituents often exist in the structure of the bifluoride anion \( [\text{HF}_2]^− \). This interaction results in an ionic compound where the bifluoride ion plays a crucial role, providing enhanced stability due to its dense packing and ionic interactions.

Ionic Composition

When exploring the ionic composition of potassium hydrogen difluoride \((\text{KHF}_2)\), it's essential to consider how the ions are arranged. This compound is composed of:

• Potassium ion \((\text{K}^+)\)
• Bifluoride ion \((\left[\text{HF}_2\right]^-\))

Rather than simply consisting of separate hydrogen \((\text{H}^+)\) and fluoride \((\text{F}^-)\) ions, \( \text{KHF}_2 \) showcases a unique combination where a hydrogen ion bridges two fluorides to form the bifluoride ion.
In terms of stability, this specific ionic arrangement permits a solid crystalline structure and maintains its integrity well in various chemical environments. Therefore, understanding the ionic composition of \( \text{KHF}_2 \) helps to explain its chemical behavior and reactions compared to compounds with more conventional ionic structures.

Bifluoride Ion

The bifluoride ion \((\left[\text{HF}_2\right]^-)\) is a key feature of potassium hydrogen difluoride. It represents a special kind of ionic interaction sometimes described as a "hydrogen bond." This structure features a single hydrogen ion shared between two fluoride ions, forming what is known as a bifluoride linkage.
The ion is particularly intriguing because it is an example of a symmetric hydrogen bond—a rare phenomenon in molecular chemistry. Some characteristic features include:

• High structural stability in its solid form
• Role in creating densely packed ionic lattices
• Uncommon occurrence compared to simpler polyatomic ions

This stability arises because the hydrogen ion effectively "holds" two fluoride ions together. Thus, when studying \( \text{KHF}_2 \), understanding the significance of the bifluoride ion can provide more profound insights into its chemical stability and behavior in reactions.