What is the vapor pressure (in torr) of a solution comprised of 220 g of CaCl₂ in 870 g of H₂O at 25 °C where H₂O has a pressure of 23.76 torr? Assume complete dissociation.
mols H2O = g/molar mass = 870/18 = about 48 but that's an estimate only.
mols CaCl2 = 220/111 = about 2 estimated.
mols CaCl2 ions = 3*2 = 6
total mols 54 so
XCaCl2 ions = 6/54 = about 0.09
XH2O = about 48/54 = about 0.81
Psoln = XH2O * Po = about 0.81 x 23.76 = ?