Write an equation to show how perchloric acid, HClO4, reacts with water. Include states of matter in your answer.
The Correct Answer and Explanation is :
The reaction of perchloric acid (HClO₄) with water can be represented as follows:
[
\text{HClO}_4 (aq) \rightarrow \text{H}^+ (aq) + \text{ClO}_4^- (aq)
]
Explanation:
Perchloric acid (HClO₄) is a strong acid, which means it completely dissociates in water. When HClO₄ is dissolved in water, it dissociates into two ions: the hydrogen ion (H⁺) and the perchlorate ion (ClO₄⁻). Here’s a breakdown of this dissociation process:
- Chemical Nature of Perchloric Acid:
- Perchloric acid (HClO₄) consists of hydrogen (H), chlorine (Cl), and oxygen (O). It is a very strong acid, meaning it ionizes completely in water, unlike weak acids that only partially dissociate.
- Dissociation in Water:
- The acid reacts with water by donating a proton (H⁺) to the water molecule. When HClO₄ dissolves in water, it breaks apart into H⁺ ions and ClO₄⁻ ions. The H⁺ ions are often referred to as protons, and they are responsible for the acidic nature of the solution. The ClO₄⁻ ion is the conjugate base of HClO₄, and in water, it does not further react or change the pH significantly.
- States of Matter:
- HClO₄ is aqueous (aq) when it dissolves in water, and the ions produced—H⁺ and ClO₄⁻—are also aqueous (aq) because they are solvated, or surrounded by water molecules, in the solution.
- Effect on pH:
- The dissociation of perchloric acid increases the concentration of hydrogen ions (H⁺) in the solution, which leads to a decrease in pH, making the solution strongly acidic.
Thus, the equation shows that HClO₄ dissociates completely in water, releasing hydrogen ions and perchlorate ions, which results in a highly acidic solution.