1. What Is The pH Calculation Formula?

The formula calculates the pH at the equivalence point for the titration of a weak base (methylamine) with a strong acid. It accounts for the hydrolysis of the conjugate acid formed at equivalence.

2. How Does The Calculator Work?

The calculator uses the formula:

Where:

• \( pK_w \) — Water ion product (typically 14.0 at 25°C)
• \( pK_b \) — Base dissociation constant of methylamine (3.36)
• \( C \) — Concentration of methylamine solution (0.180 mol/L)

Explanation: This formula derives from considering the equivalence point where the weak base is completely converted to its conjugate acid, and the pH is determined by the hydrolysis of this conjugate acid.

3. Importance Of pH Calculation

Details: Accurate pH calculation at equivalence point is crucial for understanding titration curves, selecting appropriate indicators, and determining the exact endpoint in acid-base titrations.

4. Using The Calculator

Tips: Enter pKw (typically 14.0), pKb for methylamine (3.36), and concentration (0.180 mol/L). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is this formula specific for weak base-strong acid titration?
A: Because at equivalence point, the solution contains the conjugate acid of the weak base, which hydrolyzes to give an acidic solution.

Q2: What is the typical pKb value for methylamine?
A: Methylamine has a pKb of approximately 3.36 at 25°C.

Q3: Does temperature affect the calculation?
A: Yes, pKw changes with temperature (14.0 at 25°C), so appropriate values should be used for accurate calculations.

Q4: Can this formula be used for other weak bases?
A: Yes, but you need to use the correct pKb value for the specific weak base being titrated.

Q5: Why is the concentration term included?
A: The concentration affects the extent of hydrolysis of the conjugate acid at the equivalence point.