Question

Along with the three strong acids emphasized in the chapter ( \(\mathrm{HCl}, \mathrm{HNO}_{3},\) and \(\mathrm{H}_{2} \mathrm{SO}_{4}\) ), hydrobromic acid, HBr , and perchloric acid, \(\mathrm{HClO}_{4},\) are also strong acids. Write equations for the dissociation of each of these additional strong acids in water.

Short answer

The dissociation equations for Hydrobromic acid (HBr) and Perchloric acid (HClO4) in water are as follows: 1. \(HBr + H_2O \rightarrow H_3O^{+} + Br^{-}\) 2. \(HClO_{4} + H_2O \rightarrow H_3O^{+} + ClO_4^{-}\)

Step-by-step solution

Write the general dissociation equation for strong acids in water

The general dissociation equation for the strong acids in water will have the following form: \[HA + H_2O \rightarrow H_3O^{+} + A^{-}\] where HA represents the strong acid and A- represents the conjugate base of the strong acid.

Write the dissociation equation for Hydrobromic acid (HBr)

Hydrobromic acid (HBr) is a strong acid, so applying the general strong acid dissociation equation, we have: \[HBr + H_2O \rightarrow H_3O^{+} + Br^{-}\]

Write the dissociation equation for Perchloric acid (HClO4)

Perchloric acid (HClO4) is another strong acid, so applying the general strong acid dissociation equation, we have: \[HClO_{4} + H_2O \rightarrow H_3O^{+} + ClO_4^{-}\] Now we have the dissociation equations for both Hydrobromic acid and Perchloric acid in water.

Key concepts

Chemical Equation of Strong Acids

The study of strong acids is fundamental in chemistry, especially when it comes to understanding their behavior in water. A strong acid is characterized by its complete dissociation in aqueous solution, meaning it fully separates into its constituent ions. The chemical equation representing this process is typically written as:

\[HA + H_2O \rightarrow H_3O^{+} + A^{-}\]
In this equation, \(HA\) symbolizes a generic strong acid where \(H\) is a hydrogen atom that becomes a proton, and \(A\) is the anion or the conjugate base. Water \(H_2O\) serves as the medium for the reaction, helping the acid to dissociate and form hydronium ions \(H_3O^{+}\) and the conjugate base \(A^{-}\). This full dissociation is what gives strong acids their high reactivity and the ability to drastically change the pH of a solution.

Dissociation in Water

Dissociation in water is a crucial concept for understanding acid-base chemistry. When strong acids dissolve in water, they release protons \(H^{+}\), which immediately react with water molecules to form hydronium ions \(H_3O^{+}\). This interaction can be visualized as:

\[HA_{(aq)} \rightarrow H^{+}_{(aq)} + A^{-}_{(aq)}\]
followed by:
\[H^{+}_{(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)}\]
The first equation shows the acid \(HA\) separating into protons and its anion. The subscript \((aq)\) denotes that the species are in aqueous solution. The second equation illustrates how the free protons associate with water molecules to form the hydronium ion. This process is rapid and drives the reaction to completion, resulting in no undissociated acid remaining in the solution.

Hydrobromic Acid

Hydrobromic acid (HBr) is one of the strong acids that exhibit complete dissociation in water. It's a binary acid, consisting of hydrogen and bromine. The dissociation can be represented by the chemical equation:

\[HBr_{(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)} + Br^{-}_{(aq)}\]
In this equation, \(HBr_{(aq)}\) is hydrobromic acid in an aqueous state, dissociating into hydronium ions \(H_3O^{+}\) and bromide ions \(Br^{-}\), the conjugate base. Due to its high solubility and complete dissociation, hydrobromic acid is known for its strong acidic properties, making it a powerful agent in chemical synthesis and industry.

Perchloric Acid

Perchloric acid, \(HClO_4\), stands out as another strong acid, renowned for its strength and complete dissociation in an aqueous solution. As an oxoacid, it contains oxygen in addition to hydrogen and chlorine. The dissociation reaction for perchloric acid in water is given by:

\[HClO_{4(aq)} + H_2O_{(l)} \rightarrow H_3O^{+}_{(aq)} + ClO_4^{-}_{(aq)}\]
Upon dissolving in water, \(HClO_{4}\) yields hydronium ions \(H_3O^{+}\) and perchlorate ions \(ClO_4^{-}\), which is the conjugate base. Due to its high oxidizing capability and reactivity, perchloric acid is used meticulously in laboratories and manufacturing processes. Awareness and precaution are crucial when handling \(HClO_4\) as it can be highly corrosive and reactive, especially in its concentrated form.