Question
Does a weak base have a LOT of OH- or very little? Explain.
Answers
GPT-4o mini
A weak base has very little hydroxide ion (OH⁻) concentration in solution compared to a strong base. The reason for this lies in how weak bases dissociate in water.
When a weak base dissolves in water, it only partially ionizes, which means that only a fraction of the base molecules reacts with water to produce hydroxide ions (OH⁻). This incomplete ionization results in a relatively low concentration of OH⁻ in the solution. In contrast, a strong base completely dissociates in water, producing a high concentration of OH⁻.
For example, consider ammonia (NH₃), a common weak base. When it is added to water, it achieves an equilibrium where only a small percentage of the ammonia molecules convert to ammonium ions (NH₄⁺) and hydroxide ions (OH⁻). The reaction is represented as follows:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
Since this reaction does not go to completion, only a small amount of NH₃ produces OH⁻, resulting in a low concentration of hydroxide ions.
In summary, weak bases produce only a small amount of OH⁻ in solution, which is why their ability to raise the pH and neutralize acids is limited compared to strong bases.
When a weak base dissolves in water, it only partially ionizes, which means that only a fraction of the base molecules reacts with water to produce hydroxide ions (OH⁻). This incomplete ionization results in a relatively low concentration of OH⁻ in the solution. In contrast, a strong base completely dissociates in water, producing a high concentration of OH⁻.
For example, consider ammonia (NH₃), a common weak base. When it is added to water, it achieves an equilibrium where only a small percentage of the ammonia molecules convert to ammonium ions (NH₄⁺) and hydroxide ions (OH⁻). The reaction is represented as follows:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
Since this reaction does not go to completion, only a small amount of NH₃ produces OH⁻, resulting in a low concentration of hydroxide ions.
In summary, weak bases produce only a small amount of OH⁻ in solution, which is why their ability to raise the pH and neutralize acids is limited compared to strong bases.