What is the pressure (in atm) of a gas trapped in a balloon along with water vapor at 30C if the atmospheric pressure is 1.005 atm?(Hint: Review the Dalton’s Law of partial pressures).

Answer 1

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

We have to look up the vapor pressure of water vapor at 30ºC. I found it to be 31.8 mm Hg.

Converting this to atmospheres, we have 31.8 mm Hg x 1 atm / 760 mm Hg = 0.0418 atm

1.005 atm = 0.0418 atm + P_gas

P_gas = 1.005 atm - 0.0418 atm

P_gas = 0.963 atm