Question

A strong acid has a weak bond to its acidic proton, whereas a weak acid has a strong bond to its acidic proton. Explain.

Short answer

Strong acids have weak bonds to their protons, leading to complete dissociation. Weak acids have strong bonds to their protons, leading to partial dissociation.

Step-by-step solution

Define Strong and Weak Acids

A strong acid completely dissociates in water, releasing all of its acidic protons into the solution. A weak acid only partially dissociates in water, releasing only some of its acidic protons.

Bond Strength Analysis

The bond between the acidic proton and the rest of the molecule determines how easily the proton is released. In strong acids, this bond is weak, making it easy for the proton to dissociate. In weak acids, the bond is strong, making it harder for the proton to dissociate.

Relate Bond Strength to Acid Strength

Because strong acids have weak bonds to their acidic protons, they can release protons easily, leading to complete dissociation. Conversely, weak acids have strong bonds to their protons, resulting in partial dissociation.

Key concepts

strong acids

Strong acids are known for their ability to completely dissociate in water. This means that when a strong acid is dissolved, it releases all of its acidic protons (H⁺) into the solution.
For example, hydrochloric acid (HCl) is a strong acid that fully dissociates into H⁺ and Cl^- ions.
The key to a strong acid's behavior is the weak bond between the hydrogen ion (proton) and the rest of the acid molecule. Because this bond is weak, it doesn't take much energy to break it, allowing the proton to easily leave the molecule.
This is why even in a dilute solution, a strong acid will have a high concentration of hydrogen ions, making the solution very acidic.

weak acids

In contrast to strong acids, weak acids only partially dissociate in water. This means they release only a small fraction of their acidic protons (H⁺) into the solution.
Acetic acid (CH₃COOH) is an example of a weak acid. In water, it partially dissociates into CH₃COO^- and H⁺ ions.
The bond between the proton and the rest of the weak acid molecule is relatively strong. Because this bond is strong, it requires more energy to break, so fewer protons are released into the solution.
As a result, solutions of weak acids have lower concentrations of hydrogen ions, and are less acidic compared to strong acids.

bond dissociation

Bond dissociation refers to the process of breaking the bond between the acidic proton and the rest of the acid molecule. The strength of this bond is crucial in determining the acid's overall strength:

• In strong acids, the bond is weak, making it easy to break and allowing the proton to dissociate readily.
• In weak acids, the bond is strong, which means it requires more energy to break. This results in fewer protons being released.

Understanding bond dissociation helps explain why strong acids make solutions highly acidic and why weak acids result in less acidic solutions.
When studying acids, always consider the bond strength as it directly affects how many protons are available in solution, which in turn influences the solution's pH.