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How to compute Henderson-Hasselbalch ratio in Python using UliEngineering

You can easily compute the conjugate base to acid ratio using the Henderson-Hasselbalch equation with the UliEngineering Python library:

henderson_hasselbalch_ratio.py
from UliEngineering.Chemistry import henderson_hasselbalch_ratio

# Compute ratio for pH = pKa (should be 1)
ratio = henderson_hasselbalch_ratio(4.76, 4.76)
print(f"Ratio (pH=pKa=4.76): {ratio:.4f}")

# Compute ratio for pH = pKa + 1 (should be 10)
ratio = henderson_hasselbalch_ratio(4.76, 5.76)
print(f"Ratio (pH=5.76, pKa=4.76): {ratio:.4f}")

Example output

henderson_hasselbalch_ratio_output.txt
Ratio (pH=pKa=4.76): 1.0000
Ratio (pH=5.76, pKa=4.76): 10.0000

The Henderson-Hasselbalch ratio determines the ratio of conjugate base to weak acid needed to achieve a specific pH in a buffer solution. This is essential for buffer preparation, calculating buffer capacity, and understanding acid-base equilibria in biochemical and chemical systems.

The ratio is computed using the formula: $\frac{[\text{A}^-]}{[\text{HA}]} = 10^{\text{pH} - \text{p}K_a}$, where $[\text{A}^-]$ is the concentration of the conjugate base, $[\text{HA}]$ is the concentration of the weak acid, and $\text{p}K_a$ is the acid dissociation constant. This is the inverse of the pH calculation, showing how pH changes exponentially with the concentration ratio.

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