Using the Henderson-Hasselbalch equation, determine the accuracy of the gas below. To be considered accurate, it must be within 0.03 pH unit.pH = 7.22, PCO₂ = 49 mm Hg, HCO₃^- = 20 mEq/L

Question

Quizplus · Accepted Answer

Using the Henderson-Hasselbalch equation, the pH can be calculated as follows:
pH = pKa + log ([A-]/[HA])
pKa of the bicarbonate buffer system = 6.1 (rounded off)
[A-]/[HA] = [HCO3-]/(0.03 x PCO2)
= [HCO3-]/(0.03 x 49)
= [HCO3-]/1.47
= 20/1.47
= 13.61 (rounded off)
pH = 6.1 + log (13.61)
pH = 7.23 (rounded off)
The calculated pH is within 0.03 pH unit of the given pH (7.22), thus this gas is accurate. Therefore, the best choice is B.

Using the Henderson-Hasselbalch Equation, Determine the Accuracy of the Gas