1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution during titration. It relates the pH, pKa (acid dissociation constant), and the ratio of the concentrations of the conjugate base and weak acid.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pH \) — Calculated pH value (dimensionless)
• \( pKa \) — Acid dissociation constant (dimensionless)
• \( added \) — Volume of titrant added (mL)
• \( initial \) — Initial volume of solution (40.00 mL)

Explanation: The equation calculates the pH during titration based on the ratio of added titrant to the remaining initial volume.

3. Importance of pH Calculation in Titration

Details: Accurate pH calculation is crucial for understanding titration curves, determining equivalence points, and analyzing buffer capacity in chemical reactions.

4. Using the Calculator

Tips: Enter pKa value and added volume in mL. The initial volume is fixed at 40.00 mL. Added volume must be between 0 and 40.00 mL and not equal to 20.00 mL (half-equivalence point).

5. Frequently Asked Questions (FAQ)

Q1: Why is the initial volume fixed at 40.00 mL?
A: This calculator is specifically designed for titration experiments using 40.00 mL of initial solution volume.

Q2: What happens at the half-equivalence point?
A: At added = 20.00 mL, the equation becomes undefined as the denominator becomes zero. The pH equals pKa at this point.

Q3: When is the Henderson-Hasselbalch equation most accurate?
A: The equation is most accurate when the concentrations of acid and conjugate base are relatively high and similar in magnitude.

Q4: Are there limitations to this equation?
A: The equation assumes ideal behavior and may not be accurate for very dilute solutions or when activity coefficients differ significantly from 1.

Q5: Can this calculator be used for strong acid-strong base titrations?
A: No, the Henderson-Hasselbalch equation is specifically designed for weak acid-strong base or weak base-strong acid titrations.