Answer
0.0484 g
Work Step by Step
vapor pressure of water at 22 Celsius = 19.8 mm
Calculate moles of H2O in 5.0 liters
PV= nRT , where n =moles of H2O vapor
19.8 mm x 1 atm/760mm(5 liters) = n(0.082 liter-atm/mol K)(273 + 22)
n = 0.00538 moles of H2O vapor
Volume reduced to 2.5 liters, then the moles of H2O vapor would
19.8 mm/760 mm(2.5 liters)= n(0.082)295
n = 0.00269 moles
moles of H2O that condensed = 0.00538 – 0.00269 = 0.00269
grams of H2O = 0.00269 moles x 18.0 g H2O/mole H2O = 0.0484 g
