Base dissociation constant

Base Dissociation Constant (pronunciation: /beɪs dɪˈsəʊʃɪeɪʃən ˈkɒnstənt/), also known as Base Ionization Constant or Kb, is a measure of the strength of a base in a solution. It is the equilibrium constant for the reaction of a base with water to form a hydroxide ion and the corresponding conjugate acid.

Etymology

The term "Base Dissociation Constant" is derived from the process it describes. "Base" refers to the chemical base involved in the reaction. "Dissociation" (from Latin dissociare meaning "to separate") refers to the splitting of the base into ions. "Constant" refers to the equilibrium constant, a value that remains constant for a given reaction at a specific temperature.

Definition

The Base Dissociation Constant is defined by the following equation:

Kb = [A-][OH-] / [HA]

where:

• [A-] is the concentration of the base ion
• [OH-] is the concentration of the hydroxide ion
• [HA] is the concentration of the undissociated base

Related Terms

• Acid Dissociation Constant
• Equilibrium Constant
• pKb
• pH
• pOH

See Also

• Acid-Base Reaction Theories
• Acid-Base Titration
• Acid-Base Indicator

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