Alveolar air (a mixture of nitrogen, oxygen, and carbon dioxide) has a total pressure of 0.998 atm. If the partial pressure of oxygen gas is 0.198 atm and the partial pressure of nitrogen gas is 0.770 atm, what is the partial pressure of carbon dioxide in millimeters of mercury?

22.8 mmHg

Explanation:

According to Dalton's law of partial pressures, the total pressure of a mixture of gases is obtained as the sum of the partial pressures if all the individual gases present in the mixture.

Since the total pressure of gases in the mixture is 0.998 atm, the partial pressure of carbon dioxide is;

PCO2 = [Ptotal - (PO2+ PN2)]

Hence;

PCO2 = [0.998 - (0.198 + 0.770)]

PCO2 = 0.03

Since

1 atm = 760 mmHg

0.03 atm = 0.03 × 760 /1

=22.8 mmHg