Carbonate Bicarbonate Buffer Calculator

Henderson-Hasselbalch Equation for Carbonate Buffer:

\[ pH = pKa + \log\left(\frac{[CO_3^{2-}]}{[HCO_3^-]}\right) \]

Calculated pH:

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1. What is the Carbonate Bicarbonate Buffer System?

The carbonate-bicarbonate buffer system is an important buffer in biological systems and environmental chemistry, helping to maintain stable pH levels in blood and ocean water. It consists of carbonic acid (H₂CO₃), bicarbonate (HCO₃⁻), and carbonate (CO₃²⁻) ions.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

\[ pH = pKa + \log\left(\frac{[CO_3^{2-}]}{[HCO_3^-]}\right) \]

Where:

\( pH \) — The calculated pH of the solution
\( pKa \) — Acid dissociation constant for the HCO₃⁻/CO₃²⁻ pair (typically ~10.3 at 25°C)
\( [CO_3^{2-}] \) — Concentration of carbonate ions (M)
\( [HCO_3^-] \) — Concentration of bicarbonate ions (M)

Explanation: The equation relates the pH of a solution to the ratio of the concentrations of the basic (CO₃²⁻) and acidic (HCO₃⁻) components of the buffer system.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for understanding chemical equilibria, biological systems, and environmental processes. The carbonate buffer system is particularly important in maintaining blood pH and ocean chemistry.

4. Using the Calculator

Tips: Enter the pKa value (typically 10.3 for this buffer system at 25°C), concentrations of carbonate and bicarbonate ions in molarity (M). All concentrations must be positive values.

5. Frequently Asked Questions (FAQ)

Q1: What is the typical pKa value for this system?
A: The pKa for the HCO₃⁻/CO₃²⁻ pair is approximately 10.3 at 25°C in aqueous solutions.

Q2: Where is this buffer system important?
A: This buffer is crucial in blood plasma (as part of the larger bicarbonate buffer system) and in ocean water chemistry.

Q3: What affects the pKa value?
A: Temperature and ionic strength can affect the pKa value. The calculator uses the standard value unless you input a different one.

Q4: What are typical concentration ranges?
A: In blood, bicarbonate is typically 22-26 mM. In seawater, total carbonate species are about 2 mM.

Q5: Can this be used for other buffer systems?
A: The same equation form applies to any conjugate acid-base pair, but you would need to use the appropriate pKa value.