Question

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?

Answer 1

The partial pressure of carbon dioxide is 22.8 mmHg

Step-by-step explanation:

Dalton's Law is a gas law that relates the partial pressures of the gases in a mixture. This law says that the pressure of a gas mixture is equal to the sum of the partial pressures of all the gases present.

In this case:

Ptotal=Pnitrogen + Poxygen + Pcarbondioxide

You know that:

• Ptotal= 0.998 atm
• Pnitrogen= 0.770 atm
• Poxygen= 0.198 atm
• Pcarbondioxide= ?

Replacing:

0.998 atm=0.770 atm + 0.198 atm + Pcarbondioxide

Solving:

Pcarbondioxide= 0.998 atm - 0.770 atm - 0.198 atm

Pcarbondioxide= 0.03 atm

Now you apply the following rule of three: if 1 atm equals 760 mmHg, 0.03 atm how many mmHg equals?

`Pcarbondioxide=(0.03 atm*760 mmHg)/(1 atm)`

Pcarbondioxide= 22.8 mmHg

The partial pressure of carbon dioxide is 22.8 mmHg