1. What is Ka?

Ka (acid dissociation constant) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for the dissociation reaction of an acid: HA ⇌ H⁺ + A⁻.

2. How Does the Calculator Work?

The calculator uses the Ka equation:

Where:

• \( [H^+] \) — Hydrogen ion concentration (mol/L)
• \( [A^-] \) — Conjugate base concentration (mol/L)
• \( [HA] \) — Weak acid concentration (mol/L)

Explanation: The equation calculates the acid dissociation constant based on the concentrations of hydrogen ions, conjugate base, and undissociated acid at equilibrium.

3. Importance of Ka Calculation

Details: Ka values are crucial for understanding acid strength, predicting pH of solutions, and calculating buffer capacities in chemical and biological systems.

4. Using the Calculator

Tips: Enter all concentrations in mol/L. All values must be valid positive numbers representing equilibrium concentrations.

5. Frequently Asked Questions (FAQ)

Q1: What does a larger Ka value indicate?
A: A larger Ka value indicates a stronger acid, meaning the acid dissociates more completely in solution.

Q2: How is Ka related to pKa?
A: pKa is the negative logarithm of Ka: pKa = -log₁₀(Ka). Lower pKa values indicate stronger acids.

Q3: What are typical Ka values for common acids?
A: Strong acids have Ka > 1, weak acids have Ka < 1. For example, acetic acid has Ka ≈ 1.8 × 10⁻⁵.

Q4: When should Ka be measured?
A: Ka is typically measured at equilibrium conditions, at constant temperature (usually 25°C), and in dilute aqueous solutions.

Q5: Are there limitations to this calculation?
A: This calculation assumes ideal behavior and may not account for activity coefficients, especially in concentrated solutions or non-aqueous solvents.