1. What is the Acid Dissociation Constant (Ka)?

The acid dissociation constant (Ka) is a quantitative measure of the strength of an acid in solution. It represents the equilibrium constant for the dissociation reaction of an acid into its conjugate base and a hydrogen ion.

2. How Does the Calculator Work?

The calculator uses the acid dissociation constant formula:

Where:

• \( K_a \) — Acid dissociation constant (M)
• \( [H^+] \) — Hydrogen ion concentration (M)
• \( [A^-] \) — Conjugate base concentration (M)
• \( [HA] \) — Undissociated acid concentration (M)

Explanation: The equation describes the equilibrium between an acid and its dissociation products in aqueous solution.

3. Importance of Ka Calculation

Details: Ka values are crucial for understanding acid strength, predicting reaction outcomes, calculating pH, and designing buffer solutions in chemistry and biochemistry.

4. Using the Calculator

Tips: Enter all concentrations in molarity (M). Ensure hydrogen ion concentration and acid concentration are greater than zero. Conjugate base concentration can be zero for pure acid solutions.

5. Frequently Asked Questions (FAQ)

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

Q2: How is Ka related to pKa?
A: pKa = -log₁₀(Ka). Lower pKa values correspond to 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 Ka ≈ 1.8×10⁻⁵, hydrochloric acid Ka ≈ 10⁷.

Q4: When is this calculation most accurate?
A: This calculation is most accurate for dilute solutions where activity coefficients are close to 1, and for monoprotic acids.

Q5: Can this be used for polyprotic acids?
A: For polyprotic acids, separate Ka values (Ka₁, Ka₂, etc.) must be calculated for each dissociation step.