Physics Help Forum humidity questions

 Thermodynamics and Fluid Mechanics Thermodynamics and Fluid Mechanics Physics Help Forum

 Aug 4th 2009, 01:35 AM #1 Junior Member   Join Date: Aug 2009 Posts: 1 humidity questions A volume Vi = 24.2 L of air at temperature T = 21 °C is compressed at constant temperature to a volume Vf = 11.2 L. The relative humidity of the air before compression is R = 56.7 %. Saturated water vapour in air at this temperature has a vapour pressure vp = 2.5 kPa and a density of ρ = 18.4 g.m−3. (a) What is the partial pressure of the water vapour in the air before compression? (b) What is the factor by which each non-condensing component of air (e.g. oxygen , nitrogen, etc) has its partial pressure increased in the compression? (c) What is the density the water vapour would have had following compression if it behaved like an ideal gas instead of experiencing partial condensation? (d) What is the density of water vapour in the air following compression? (e) What mass of water condenses out because of the compression? could someone please help, i can't seem to find a question like this in any of the books, so need help with solving them.
 Aug 4th 2009, 02:11 PM #2 Junior Member   Join Date: Aug 2009 Posts: 6 For (a) you should try using the formula Relative Humidity = Partial Pressure / Vp X 100 And rearrange for Partial Pressure