1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of concentrations of a weak acid and its conjugate base in solution. It's particularly useful for buffer solutions and predicting the pH of acid-base systems.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pH \) — The calculated pH of the solution (dimensionless)
• \( pKa \) — The acid dissociation constant (dimensionless)
• \( [base] \) — Concentration of the conjugate base (mol/L)
• \( [acid] \) — Concentration of the weak acid (mol/L)

Explanation: The equation shows that pH equals pKa when the concentrations of acid and base are equal, and changes logarithmically with their ratio.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for understanding chemical reactions, biological systems, and preparing buffer solutions in laboratory and industrial settings.

4. Using the Calculator

Tips: Enter pKa value, base concentration and acid concentration in mol/L. All values must be valid (acid concentration must be > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the valid range for pH values?
A: The pH scale typically ranges from 0 to 14 in aqueous solutions, with 7 being neutral.

Q2: How accurate is this calculation?
A: The equation assumes ideal behavior and is most accurate for dilute solutions (concentrations < 0.1 M).

Q3: What if my acid concentration is zero?
A: The equation becomes undefined when [acid] = 0. Always ensure [acid] > 0 for valid calculations.

Q4: Can I use this for polyprotic acids?
A: For polyprotic acids, you would need to consider each dissociation step separately with its own pKa value.

Q5: What temperature is this valid for?
A: The equation is typically used for standard conditions (25°C), as pKa values are temperature-dependent.