1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation relates pH, pKa (acid dissociation constant), and the ratio of concentrations of the base and acid forms of a buffer solution. It's widely used in chemistry and biochemistry to calculate the pH of buffer solutions.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pH \) — Negative logarithm of hydrogen ion concentration (dimensionless)
• \( pKa \) — Negative logarithm of acid dissociation constant (dimensionless)
• \( [base] \) — Concentration of the base form (mol/L)
• \( [acid] \) — Concentration of the acid form (mol/L)

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

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for preparing buffer solutions in laboratory settings, pharmaceutical formulations, and biological research where maintaining specific pH ranges is essential.

4. Using the Calculator

Tips: Enter pKa value, base concentration and acid concentration in mol/L. All values must be positive numbers. The calculator will compute the pH of the buffer solution.

5. Frequently Asked Questions (FAQ)

Q1: What is a good buffer range?
A: A buffer works best when pH is within ±1 unit of its pKa. The buffer capacity is highest when pH = pKa.

Q2: What are common buffer systems?
A: Common systems include acetate (pKa 4.76), phosphate (pKa 7.21), and Tris (pKa 8.07).

Q3: Why use logarithmic scale?
A: The logarithmic scale (pH) makes it easier to work with the very small concentrations of H+ ions in solution.

Q4: Are there limitations to this equation?
A: The equation assumes ideal behavior and may be less accurate for very concentrated solutions or when ionic strength is high.

Q5: How temperature affects pH?
A: Both pKa and pH are temperature-dependent. Most pKa values are reported at 25°C.