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 and is a crucial parameter in acid-base chemistry.

2. How Does the Calculator Work?

The calculator uses the acid dissociation constant formula:

Where:

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

Calculation Process: The calculator first converts pH to hydrogen ion concentration using \( [H^+] = 10^{-pH} \), then applies the Ka formula using the provided concentrations.

3. Importance of Ka Calculation

Details: Ka values are essential for understanding acid strength, predicting acid-base reaction outcomes, calculating pH of buffer solutions, and determining the extent of acid dissociation in various chemical and biological systems.

4. Using the Calculator

Tips: Enter pH value (0-14), conjugate base concentration [A⁻] in mol/L, and weak acid concentration [HA] in mol/L. Ensure all values are positive and pH is within the valid range.

5. Frequently Asked Questions (FAQ)

Q1: What does a larger Ka value indicate?
A: Larger Ka values indicate stronger acids, as they dissociate more completely in solution.

Q2: How is pKa related to Ka?
A: pKa = -log(Ka). Smaller pKa values correspond to stronger acids.

Q3: What are typical Ka value ranges?
A: Strong acids have Ka > 1, weak acids have Ka < 1, with very weak acids having Ka values as low as 10^-10 or smaller.

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

Q5: Can this be used for polyprotic acids?
A: For polyprotic acids, separate Ka values must be calculated for each dissociation step using appropriate concentrations.