1. What is Ka Calculation?

Ka calculation determines the acid dissociation constant from pH data using the relationship between pH, pKa, and the concentrations of conjugate base and weak acid in a buffer solution.

2. How Does the Calculator Work?

The calculator uses the following formulas:

Where:

• \( Ka \) — Acid dissociation constant (M)
• \( pKa \) — Negative logarithm of Ka
• \( pH \) — Measure of acidity/basicity (dimensionless)
• \( [A^-] \) — Concentration of conjugate base (M)
• \( [HA] \) — Concentration of weak acid (M)

Explanation: The calculation derives Ka from pH measurements in buffer solutions using the Henderson-Hasselbalch relationship.

3. Importance of Ka Calculation

Details: Ka values are fundamental in acid-base chemistry, determining acid strength, predicting buffer capacity, and understanding chemical equilibrium in aqueous solutions.

4. Using the Calculator

Tips: Enter pH value (0-14), concentrations of conjugate base [A⁻] and weak acid [HA] in molarity (M). All concentrations must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What does Ka represent?
A: Ka represents the equilibrium constant for acid dissociation, indicating acid strength. Larger Ka values indicate stronger acids.

Q2: How is pKa related to Ka?
A: pKa is the negative base-10 logarithm of Ka (pKa = -log₁₀Ka). Lower pKa values indicate stronger acids.

Q3: When is this calculation most accurate?
A: This method works best for weak acids in buffer solutions where the Henderson-Hasselbalch equation is valid.

Q4: What are typical Ka values?
A: Strong acids have Ka > 1, weak acids have Ka < 1. Very weak acids can have Ka values as small as 10⁻¹⁰ or less.

Q5: Can this be used for polyprotic acids?
A: This calculation is for monoprotic acids. Polyprotic acids require separate calculations for each dissociation step.