OH-

Definition

OH- is the hydroxide ion, a negatively charged species consisting of one oxygen atom and one hydrogen atom. It is a key component in understanding the Brønsted-Lowry definition of acids and bases, which describes chemical species in terms of their ability to donate or accept protons (H+ ions).

5 Must Know Facts For Your Next Test

1. The hydroxide ion (OH-) is a Brønsted-Lowry base, as it can accept a proton (H+) to form water (H2O).
2. The strength of a base is determined by its ability to accept protons, with stronger bases having a greater tendency to accept protons.
3. The conjugate base of a weak acid is a stronger base, and the conjugate acid of a weak base is a stronger acid.
4. The pH of a solution is determined by the concentration of H+ ions, with a pH less than 7 indicating an acidic solution and a pH greater than 7 indicating a basic solution.
5. The autoionization of water produces equal concentrations of H+ and OH- ions, with the product of their concentrations being the equilibrium constant (Kw) for water.

Review Questions

• Explain how the hydroxide ion (OH-) is classified as a Brønsted-Lowry base and its role in determining the pH of a solution.
  • The hydroxide ion (OH-) is classified as a Brønsted-Lowry base because it can accept a proton (H+) to form water (H2O). This ability to accept protons is the defining characteristic of a Brønsted-Lowry base. The concentration of H+ and OH- ions in a solution determines the pH, with a higher concentration of OH- ions resulting in a basic (pH > 7) solution. The autoionization of water produces equal concentrations of H+ and OH- ions, and the product of their concentrations is the equilibrium constant (Kw) for water.
• Describe the relationship between the strength of a base and its ability to accept protons, and explain how this relates to the concept of conjugate acid-base pairs.
  • The strength of a base is determined by its ability to accept protons. Stronger bases have a greater tendency to accept protons, while weaker bases have a lesser tendency. This concept is closely tied to the idea of conjugate acid-base pairs, where the conjugate base of a weak acid is a stronger base, and the conjugate acid of a weak base is a stronger acid. The strength of a base is inversely related to the strength of its conjugate acid, and vice versa. Understanding this relationship is crucial for predicting the direction of proton transfer reactions and for determining the pH of a solution.
• Analyze the role of the hydroxide ion (OH-) in the context of the Brønsted-Lowry definition of acids and bases, and explain how it contributes to our understanding of acid-base chemistry.
  • The hydroxide ion (OH-) is a central component in the Brønsted-Lowry definition of acids and bases, which describes chemical species in terms of their ability to donate or accept protons (H+ ions). As a Brønsted-Lowry base, the hydroxide ion can accept a proton to form water (H2O), making it a key player in acid-base reactions. The strength of a base, such as the hydroxide ion, is determined by its tendency to accept protons, which is inversely related to the strength of its conjugate acid. This understanding of acid-base chemistry, including the role of the hydroxide ion, is essential for predicting the direction of proton transfer reactions, determining the pH of solutions, and explaining the behavior of acids and bases in various chemical systems.

Related terms

Brønsted-Lowry Acid: A Brønsted-Lowry acid is a species that can donate a proton (H+) to another species.

Brønsted-Lowry Base: A Brønsted-Lowry base is a species that can accept a proton (H+) from another species.

Conjugate Acid-Base Pair: A conjugate acid-base pair consists of an acid and its corresponding base, or a base and its corresponding acid, formed by the gain or loss of a proton.