Question

When an ionic substance such as potassium bromide, KBr, dissolves, the resulting solution contains separate, hydrated ions that behave ________ of one another.

Short answer

When an ionic substance such as potassium bromide, KBr, dissolves, the resulting solution contains separate, hydrated ions that behave independently of one another.

Step-by-step solution

Understand the Dissolving Process of an Ionic Substance

When an ionic substance (like KBr) dissolves in water, its ions are surrounded by water molecules. The positive and negative ions in the compound are attracted to the partial negative (oxygen) and partial positive (hydrogen) charges on the water molecules, respectively. This process, known as "hydration," leads to the formation of a solution containing separate, hydrated ions.

Analyze the Interaction of Hydrated Ions

Once an ionic substance dissolves in water, the hydrated ions behave independently of one another. This is due to the electrostatic attractions between the ions and the water molecules essentially overcoming the strong ionic bonds in the solid. As a result, the hydrated ions are free to move and interact with other ions and molecules in the solution, without being influenced by other hydrated ions from the same ionic substance.

Complete the Sentence

Now we can use our understanding of the behavior of hydrated ions to complete the given sentence: When an ionic substance such as potassium bromide, KBr, dissolves, the resulting solution contains separate, hydrated ions that behave independently of one another.

Key concepts

Hydration

Hydration is the process that occurs when ions from an ionic substance dissolve in water. During hydration, the ions in the compound become surrounded by water molecules. The oxygen part of the water molecule, which has a somewhat negative charge, is attracted to positively charged ions. Likewise, the hydrogen parts, having a slightly positive charge, are attracted to negatively charged ions.
This arrangement allows water molecules to effectively separate ions from each other.

• The positive ions are surrounded by the negative oxygen ends of water molecules.
• Negative ions are enveloped by the positive hydrogen ends.

This entire process facilitates the formation of a solution where ions are evenly dispersed in the liquid. By having ions surrounded in this manner, they become stabilized, which is essential for a complete dissolution.

Ionic Substance

An ionic substance consists of a lattice structure formed by positive and negative ions held together by strong ionic bonds. Potassium bromide (KBr) is an example of such a substance.
In solid form, these ions are tightly bound in a rigid framework, making them immobile.

• This bond is due to the electrostatic attraction between oppositely charged ions.
• The overall solid is neutral since the charges of the ions counterbalance each other.

When immersed in water, these ionic bonds are disrupted as water molecules surround each ion, leading to the solid dissolving. The ions are thus freed from their fixed positions, allowing them to move about independently, resulting in a liquid solution.

Potassium Bromide

Potassium bromide (KBr) is a classic example of an ionic compound. It is composed of potassium ions (\(K^+\)) and bromide ions (\(Br^-\)). When potassium bromide is added to water, it undergoes a quick dissolving process.
The KBr dissociates into its constituent ions, which are then subjected to the hydration process.

• Each potassium ion becomes surrounded by water molecules, attracted by their negative oxygen atoms.
• The bromide ions are also enclosed by water molecules, but with the positive hydrogen atoms facing the ion.

The separated ions retain their charges, and they move freely in the solution, demonstrating their complete dissociation from each other.

Hydrated Ions

Once ions are separated and enveloped by water molecules, they are referred to as 'hydrated ions.' These ions are now free and independent in the aqueous solution. The hydrated ions' motions are not influenced by other ions from the same compound, allowing them to interact freely with other substances in the solution.
Key characteristics of hydrated ions include:

• They operate independently in the solution, meaning each ion can travel unimpeded by others.
• The hydration shell around each ion provides a barrier which helps keep the ions stably dissolved.

This independence is crucial for various chemical reactions and processes that occur in solutions, as it allows ions to participate without restriction, contributing to the dynamic nature of aqueous reactions.