Which equation represents the Henderson-Hasselbalch equation as applied to blood pH?

The Henderson-Hasselbalch equation is a fundamental formula in acid-base chemistry that relates the pH of a solution to the pKa of an acid and the ratio of the concentrations of its conjugate base and acid. In the context of blood pH, it specifically applies to the bicarbonate buffering system.

In this system, bicarbonate (HCO3-) acts as the base, while carbon dioxide (CO2) plays a role as the acid component when it forms carbonic acid (H2CO3) in equilibrium with bicarbonate. The correct representation of the Henderson-Hasselbalch equation in this context helps quantify blood pH, depending on the concentration of bicarbonate and the partial pressure of carbon dioxide (PCO2).

The chosen equation accurately reflects this relationship: it adjusts the ratio of bicarbonate to a factor involving carbon dioxide, incorporating the conversion factor of 0.03. This factor accounts for the solubility of CO2 in blood, ensuring that the equation correlates properly with physiological conditions. The presence of 0.03 is essential as it converts the partial pressure of CO2 to the concentration of dissolved CO2 in the blood, making the formula applicable to the pH determination in a biological context