Question

What happens when a strong acid such as HBr is dissolved in water?

Short answer

When HBr is dissolved in water, it dissociates into H⁺ and Br⁻, increasing the solution's acidity.

Step-by-step solution

Understanding Strong Acids

A strong acid is defined as one that completely dissociates in water. This means it releases all of its hydrogen ions (H⁺) into the solution. In this exercise, we are working with Hydrogen Bromide (HBr), which is known as a strong acid.

Dissociation Reaction

When Hydrogen Bromide (HBr) is dissolved in water, it dissociates completely into hydrogen ions (H⁺) and bromide ions (Br⁻). The chemical equation for this process is: \[ \text{HBr (aq)} \rightarrow \text{H}^+ (aq) + \text{Br}^- (aq) \] This equation shows the complete separation of HBr into its ions.

Hydration of Ions

Once dissociation occurs, the hydrogen ions (H⁺) do not remain isolated. Instead, they interact with water molecules to form hydronium ions (H₃O⁺). This process can be represented as: \[ \text{H}^+ (aq) + \text{H}_2\text{O (l)} \rightarrow \text{H}_3\text{O}^+ (aq) \] Similarly, the bromide ions (Br⁻) are also surrounded by water molecules, becoming solvated.

Effect on Solution

The presence of hydronium ions (H₃O⁺) increases the acidity of the solution. The solution becomes acidic due to the high concentration of these ions, which result from the complete dissociation of the strong acid.

Key concepts

Strong Acids

Strong acids are fascinating substances in the world of chemistry. They are characterized by their almost complete dissociation when they come into contact with water. This means that each molecule of a strong acid releases its available hydrogen ions, making the acid fully ionized in a solution.

When considering strong acids like hydrogen bromide (HBr), the primary focus is on their ability to donate protons. A strong acid essentially "lets go" of its hydrogen ion very easily, which is a key trait setting them apart from weaker acids. This is important because the stronger the acid, the more it influences the acidity of a solution.

Here are a few key traits of strong acids:

• They completely dissociate in water.
• They serve as excellent proton donors.
• They contribute significantly to the acidity of solutions they are dissolved in.

Dissociation Reaction

The dissociation reaction is a crucial process that defines the behavior of strong acids in aqueous solutions. For a strong acid such as HBr, the interaction with water leads to complete dissociation, meaning the acid splits into its component ions.

In the case of HBr, the dissociation process follows a straightforward chemical reaction: \[ \text{HBr (aq)} \rightarrow \text{H}^+ (aq) + \text{Br}^- (aq) \]

Each molecule of HBr contributes a hydrogen ion \((\text{H}^+)\) and a bromide ion \((\text{Br}^-)\) to the solution. This total separation is what enables strong acids to significantly increase the concentration of hydrogen ions in the solution, impacting its acidity.

Understanding this reaction is critical for grasping why strong acids are so effective at changing the chemical properties of a solution.

Hydronium Ions

Hydronium ions are an essential part of understanding how acids behave in water. When hydrogen ions \((\text{H}^+)\) are released from a strong acid like HBr, they do not remain isolated for long. Instead, they swiftly associate with water molecules to form hydronium ions \((\text{H}_3\text{O}^+)\).

The transformation can be expressed as: \[ \text{H}^+ (aq) + \text{H}_2\text{O (l)} \rightarrow \text{H}_3\text{O}^+ (aq) \]

This interaction is a vital step because hydronium ions are a more stable and naturally occurring form in aqueous solutions. They are essentially what makes a solution acidic. The more hydronium ions present, the higher the acidity level of the solution.

Consider these significant points about hydronium ions:

• They result from the interaction of hydrogen ions with water molecules.
• They increase the acidity of an aqueous solution.
• They are a central concept in the study of acid-base chemistry.

Solution Acidity

Solution acidity is directly influenced by the concentration of hydrogen ions, specifically hydronium ions \((\text{H}_3\text{O}^+)\), resulting from the dissociation of strong acids. It is these ions that determine the pH level, which is a measure of the acidity or basicity of a solution.

When a strong acid like HBr dissociates in water, it significantly raises the concentration of hydronium ions. This increase in \(\text{H}_3\text{O}^+\) concentration leads to a lower pH, indicating a more acidic solution.

Here’s a quick summary of what happens when a strong acid like HBr is dissolved in water:

• Complete dissociation of the acid increases hydronium ion concentration.
• Higher hydronium ion concentration lowers the pH, making the solution more acidic.
• The acidity level is a crucial factor in various chemical reactions and processes.

Understanding solution acidity is essential for predicting and controlling chemical reactions in a variety of contexts, from industrial applications to biological processes.