Dissociation Constant Formula:
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Definition: This calculator determines the dissociation constant (Kₐ) of a weak acid based on its initial concentration and degree of dissociation.
Purpose: It helps chemists and students quantify acid strength and understand acid-base equilibrium in solutions.
The calculator uses the formula:
Where:
Explanation: The dissociation constant is calculated by multiplying the initial concentration by the square of the degree of dissociation.
Details: The Kₐ value indicates acid strength - smaller values mean weaker acids that dissociate less in solution.
Tips: Enter the initial acid concentration and degree of dissociation (between 0 and 1). Both values must be positive.
Q1: What is degree of dissociation?
A: It's the fraction of acid molecules that dissociate into ions in solution (0 = no dissociation, 1 = complete dissociation).
Q2: What's a typical Kₐ value for weak acids?
A: Weak acids typically have Kₐ values between 10⁻² and 10⁻¹⁰ mol/m³.
Q3: Why do we square the degree of dissociation?
A: The square accounts for the equilibrium concentrations of both the hydrogen ion and conjugate base in the dissociation reaction.
Q4: Can I use molarity (mol/L) instead of mol/m³?
A: Yes, but be consistent with units. 1 M = 1000 mol/m³. The calculator will give Kₐ in the same units as C₀.
Q5: What if my degree of dissociation is very small?
A: For very small α values (less than 0.05), you can use the approximation Kₐ ≈ C₀ × α² without significant error.