1. What is pH Calculation from Titration Curve?

pH calculation from titration curve involves determining the pH value at specific points during a titration process, particularly at the half-equivalence point where pH equals pKa.

2. How Does the Calculator Work?

The calculator uses the fundamental relationship:

Where:

• \( pH \) — pH value (dimensionless)
• \( pKa \) — Acid dissociation constant (dimensionless)

Explanation: At the half-equivalence point of a titration curve, the concentration of the acid equals the concentration of its conjugate base, making pH equal to pKa.

3. Importance of pH Calculation

Details: Accurate pH calculation from titration curves is essential for determining acid dissociation constants, understanding buffer capacity, and analyzing chemical equilibrium in various solutions.

4. Using the Calculator

Tips: Enter the pKa value obtained from your titration curve analysis. The calculator will compute the pH at the half-equivalence point.

5. Frequently Asked Questions (FAQ)

Q1: Why is pH equal to pKa at half-equivalence point?
A: At half-equivalence point, [HA] = [A⁻], making the Henderson-Hasselbalch equation simplify to pH = pKa + log(1) = pKa.

Q2: What is the significance of the half-equivalence point?
A: The half-equivalence point indicates where the buffering capacity is maximum and provides a direct measurement of pKa.

Q3: How accurate is this calculation?
A: This calculation provides excellent accuracy for weak acid-strong base titrations under ideal conditions.

Q4: Can this be used for polyprotic acids?
A: For polyprotic acids, each equivalence point has its own half-equivalence point where pH equals the corresponding pKa value.

Q5: What factors can affect the accuracy of this calculation?
A: Temperature, ionic strength, and non-ideal behavior can affect the accuracy, though the relationship remains fundamentally valid.