1. What is the Weak Acid-Strong Base Titration Equation?

The weak acid-strong base titration equation calculates the pH at the equivalence point of a titration between a weak acid and a strong base. This equation accounts for the hydrolysis of the conjugate base formed at the equivalence point.

2. How Does the Calculator Work?

The calculator uses the weak acid-strong base titration equation:

Where:

• \( pK_w \) — Water ion product (typically 14.00 at 25°C)
• \( pK_a \) — Acid dissociation constant of the weak acid
• \( C \) — Concentration of the salt formed at equivalence point (mol/L)

Explanation: This equation combines the effects of water autoionization, acid strength, and concentration to determine the pH at the equivalence point where the weak acid has been completely neutralized by the strong base.

3. Importance of pH Calculation at Equivalence Point

Details: Accurate pH calculation at the equivalence point is crucial for determining the appropriate indicator for titration experiments, understanding the buffering capacity of the system, and analyzing acid-base equilibrium in chemical reactions.

4. Using the Calculator

Tips: Enter pKw (typically 14.00), pKa of the weak acid, and concentration of the resulting salt. All values must be positive numbers with concentration > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the pH at equivalence point not 7 for weak acid-strong base titrations?
A: The conjugate base of the weak acid hydrolyzes water, producing OH⁻ ions and making the solution basic at the equivalence point.

Q2: What is the typical range of pKa values for weak acids?
A: Weak acids typically have pKa values between 2-12, with most common weak acids falling in the 3-7 range.

Q3: How does temperature affect pKw?
A: pKw decreases with increasing temperature (e.g., 13.99 at 37°C, 13.40 at 60°C).

Q4: When is this equation not applicable?
A: This equation assumes ideal behavior, dilute solutions, and that the concentration term C represents the formal concentration of the salt at equivalence.

Q5: How accurate is this calculation for real titrations?
A: The equation provides a good approximation, but actual experimental results may vary due to activity coefficients, temperature effects, and other non-ideal behaviors.