Dissociation Constant Formula:
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Definition: The dissociation constant (Kb) of a weak base is the equilibrium constant for its dissociation reaction in aqueous solution.
Purpose: It quantifies the base's strength - higher Kb values indicate stronger bases that dissociate more completely in water.
The calculator uses the formula:
Where:
Explanation: The formula relates the base's initial concentration and its degree of dissociation to calculate the equilibrium constant.
Details: Knowing Kb helps predict a base's behavior in solution, calculate pH, and understand chemical equilibrium in acid-base systems.
Tips: Enter the initial concentration in mol/m³ and degree of dissociation (between 0 and 1). Both values must be positive numbers.
Q1: What is the degree of dissociation?
A: It's the fraction of base molecules that dissociate into ions in solution (0 = none dissociated, 1 = fully dissociated).
Q2: What are typical Kb values?
A: Weak bases typically have Kb values between 10⁻² and 10⁻¹⁰. Strong bases have much higher Kb values.
Q3: How does concentration affect Kb?
A: Kb is constant for a given base at a specific temperature, independent of concentration.
Q4: What's the relationship between Kb and pKb?
A: pKb = -log10(Kb). Lower pKb values indicate stronger bases.
Q5: When is this formula valid?
A: For weak bases where α is small (typically < 0.05 or 5% dissociation), otherwise more complex calculations are needed.