A breathing mixture used by deep-sea divers contains helium, oxygen, and carbon dioxide What is the partial pressure of oxygen at 101.4101.4 kPakPa if P_(He)PHe = 82.582.5 kPakPa and P_(CO2)PCO2 = .4.4 kPakPa?

2 Answers
Feb 22, 2016

The partial pressure of oxygen in the mixture is 18.5 kPa.

Explanation:

The total pressure is the sum of the partial pressures of the given gases.

P_"Total"=P_"He"+P_"CO2"+P_"O2"PTotal=PHe+PCO2+PO2

Rearrange the equation to isolate P_"O2"PO2, substitute the given values into the equation and solve.

P_"O2"=P_"Total"-(P_"He"+P_"CO2")PO2=PTotal(PHe+PCO2)

P_"O2"=101.4"kPa"+(82.5"kPa"+0.4"kPa")PO2=101.4kPa+(82.5kPa+0.4kPa)

P_"O2"=18.5"kPa"PO2=18.5kPa

Feb 22, 2016

The total pressure of 101.4101.4 kPakPa is made up of the sum of the partial pressures of the three gases, so P_(O2)=101.4-82.5-0.4=18.5PO2=101.482.50.4=18.5 kPakPa.

Explanation:

In a little more detail, the total pressure is the sum of the partial pressures of the gases present:

P_("tot")=P_(O2)+P_(He)+P_(CO2)Ptot=PO2+PHe+PCO2

We want to know the partial pressure of oxygen, P_(O2)PO2, so we rearrange:

P_(O2)=P_("tot")-P_(He)-P_(CO2)PO2=PtotPHePCO2

Substituting in the known values gives the answer shown above.