1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation relates the pH of a solution to the pKa of the acid and the ratio of the concentrations of the conjugate base and acid. It's particularly useful for calculating the pH of buffer solutions.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pKa \) — Acid dissociation constant (dimensionless)
• \( [base] \) — Concentration of conjugate base (mol/L)
• \( [acid] \) — Concentration of weak acid (mol/L)

Explanation: The equation shows that the pH of a buffer solution depends on the pKa of the weak acid and the ratio of the concentrations of the conjugate base to the acid.

3. Importance of Buffer pH Calculation

Details: Buffer solutions resist changes in pH when small amounts of acid or base are added. Accurate pH calculation is crucial in biochemical systems, pharmaceutical formulations, and many industrial processes.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What is the range where this equation is valid?
A: The equation works best when the pH is within ±1 unit of the pKa (where the buffer is most effective).

Q2: Can I use molarity or activity in this equation?
A: Strictly speaking, activities should be used, but for dilute solutions (<0.1 M), molarity is a good approximation.

Q3: What if my acid concentration is zero?
A: The equation becomes undefined when [acid] = 0. This calculator requires [acid] > 0.

Q4: Does temperature affect the calculation?
A: Yes, pKa values are temperature-dependent, but this calculator uses the pKa value you provide.

Q5: Can I calculate base/acid ratio from pH and pKa?
A: Yes, you can rearrange the equation to solve for [base]/[acid] = 10^(pH - pKa).