A gas sample is made entirely of carbon dioxide and water, and there are 300 moles of CO2 and 500 moles of H2O. If the total pressure of the sample is 21 atm, what is the partial pressure of H2O ? Ptotal = Pa + Pb+ Pc Pa = Xa(Ptotal)

Explanation:

Total moles = 300 + 500 = 800 moles

mole fraction of carbon dioxide = 300 / 800 = 3 / 8

water = 500 / 800 = 5 / 8

Total pressure = 21 atm

partial pressure of water = total pressure x mole fraction of water

= 21 x 5 / 8

= 13.125 atm