1. What is the pH Calculation Formula?

The formula \( pH = pKa - \frac{1}{2} \log(C) \) is used to calculate the pH of a weak acid solution when equal volumes are mixed, resulting in an effective concentration C = 0.01 M for HOCl.

2. How Does the Calculator Work?

The calculator uses the pH formula:

Where:

• \( pKa \) — Acid dissociation constant (dimensionless)
• \( C \) — Effective concentration after mixing (0.01 mol/L)

Explanation: When equal volumes of 0.02 M HOCl are mixed, the concentration becomes 0.01 M. The formula accounts for the weak acid behavior using its pKa value.

3. Importance of pH Calculation

Details: Accurate pH calculation is essential for understanding acid-base properties, chemical reactions, and biological systems where HOCl is involved.

4. Using the Calculator

Tips: Enter the pKa value for HOCl. The calculator will automatically use the effective concentration C = 0.01 M to compute the pH.

5. Frequently Asked Questions (FAQ)

Q1: Why is the effective concentration 0.01 M?
A: When equal volumes of 0.02 M solution are mixed, the concentration is halved to 0.01 M due to dilution.

Q2: What is the typical pKa value for HOCl?
A: The pKa for hypochlorous acid (HOCl) is approximately 7.53 at 25°C.

Q3: When is this formula applicable?
A: This formula is specifically for weak acids when equal volumes are mixed, resulting in the described concentration change.

Q4: Are there limitations to this calculation?
A: This calculation assumes ideal conditions and may not account for temperature variations or ionic strength effects.

Q5: Can this be used for other weak acids?
A: Yes, the same formula applies to other weak acids when mixing equal volumes, though the pKa value will differ.