Base-ionization constant (Kb)
Definition
The base-ionization constant (Kb) quantifies the strength of a base in a solution. It is the equilibrium constant for the dissociation of a base into its conjugate acid and hydroxide ion.
5 Must Know Facts For Your Next Test
- Kb is used to compare the strengths of different bases; a higher Kb value indicates a stronger base.
- The formula for Kb is $K_b = \frac{[BH^+][OH^-]}{[B]}$, where [BH+] is the concentration of the conjugate acid, [OH-] is the concentration of hydroxide ions, and [B] is the concentration of the base.
- Bases with Kb values greater than $1 \times 10^{-2}$ are considered strong bases, while those with lower values are weak bases.
- Kb values can be used to calculate pOH and subsequently pH, important for understanding the acidity or basicity of solutions.
- There is an inverse relationship between Ka (acid dissociation constant) and Kb for conjugate acid-base pairs: $K_a \times K_b = K_w$ (where $K_w$ is the ion-product constant for water).
Review Questions
- What does a higher Kb value indicate about a base's strength?
- Write down the formula for calculating Kb.
- How are Ka and Kb related in terms of their product?
"Base-ionization constant (Kb)" appears in:
Study guides (1)
Related terms
Acid Dissociation Constant (Ka): A quantitative measure of the strength of an acid in solution; it represents how completely an acid dissociates into its ions.
pOH: A measure of hydroxide ion concentration; calculated as $pOH = -\log[OH^-]$.
Ion-product Constant for Water (Kw): $Kw$ represents the product of hydrogen ion concentration and hydroxide ion concentration in water at a specific temperature, typically $1.0 \times 10^{-14}$ at room temperature.
