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

This equation calculates the pH at the equivalence point for weak base-strong acid titration. The equivalence point occurs when moles of acid equal moles of base, resulting in the hydrolysis of the conjugate acid.

2. How Does the Calculator Work?

The calculator uses the pH equation:

Where:

• \( pK_w \) — Water ion product (typically 14 at 25°C)
• \( pK_b \) — Base dissociation constant of the weak base
• \( C \) — Concentration of the salt at equivalence point (mol/L)

Explanation: This equation accounts for the hydrolysis of the conjugate acid formed at the equivalence point, where the solution becomes acidic due to the weak conjugate acid.

3. Importance of pH Calculation at Equivalence Point

Details: Accurate pH calculation at equivalence point is crucial for determining the appropriate indicator choice in titration experiments and understanding the acid-base properties of the resulting solution.

4. Using the Calculator

Tips: Enter pKw (typically 14), pKb of the weak base, and concentration C at equivalence point. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is the pH acidic at equivalence point?
A: The conjugate acid of the weak base hydrolyzes water, producing H⁺ ions and making the solution acidic.

Q2: What is the typical range of pKb values?
A: pKb values typically range from 2-12 for common weak bases, with lower values indicating stronger bases.

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 and may not be accurate for very dilute solutions or when additional equilibria are present.

Q5: How to choose an indicator for this titration?
A: Choose an indicator whose pH transition range includes the calculated equivalence point pH.