posted by kat .
By how much will the vapor pressure of water decrease if a solution at 40.0°C is produced by dissolving 16.0212 g of K3PO4 (formula mass = 212.30 g/mol) with 40.8480 g of water. The vapor pressure of pure water at this temperature is 55.30 mmHg. If the solute is ionic, assume that it is completely ionic!
we use Raoults law but i don't know how to use the g given
mols K3PO4 = grams/molar mass
mols H2O = grams/molar mass
Total mols = ?
XK3PO4 = ?
XH2O = ?
NOTE. Remember i, the van't Hoff factor for H3PO4 is 3and take that into account in the above, or at least before calculate ing vapor pressure.