1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution from the concentrations of a weak acid and its conjugate base. For the carbonic acid system, it relates pH to the ratio of bicarbonate to dissolved carbon dioxide.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pH \) — pH value (dimensionless)
• \( pKa1 \) — Acid dissociation constant for carbonic acid (typically 6.1)
• \( [HCO_3^-] \) — Bicarbonate concentration (mol/L)
• \( [CO_2] \) — Dissolved carbon dioxide concentration (mol/L)

Explanation: The equation shows that pH is determined by the ratio of bicarbonate to carbon dioxide concentrations, with pKa1 representing the equilibrium constant.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for understanding acid-base balance in biological systems, particularly in blood chemistry and respiratory physiology.

4. Using the Calculator

Tips: Enter pKa1 value (typically 6.1 for carbonic acid), bicarbonate concentration in mol/L, and carbon dioxide concentration in mol/L. All concentrations must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical pKa1 value for carbonic acid?
A: The pKa1 for carbonic acid is typically 6.1 at physiological temperatures.

Q2: What are normal bicarbonate and CO₂ levels in blood?
A: Normal arterial bicarbonate is 22-26 mmol/L, while dissolved CO₂ is approximately 1.2 mmol/L.

Q3: How does this relate to blood pH?
A: This equation forms the basis for understanding respiratory and metabolic acid-base disorders in clinical medicine.

Q4: Are there limitations to this equation?
A: The equation assumes ideal behavior and may not account for all ionic interactions in complex biological systems.

Q5: Can this be used for other buffer systems?
A: Yes, the Henderson-Hasselbalch equation can be applied to any weak acid-conjugate base buffer system with the appropriate pKa value.