A vapor pressure chemistry problem?
The density of a .438 M solution of potassium chromate K2CrO4 at 298K is 1.063g/mL. Calculate the vapor pressure of water above the solution. The vapor pressure of pure water at this temperature is .0313 atm. Assume complete dissociation.
Comments
moles K2CrO4 = 0.438
volume solution = 1 L
mass solution = 1000 mL x 1.063 g/mL=1063 g
mass K2CrO4 = 0.438 x 194.19 g/mol=85.1 g
mass water = 1063 - 85.1 = 977.9 g
moles water = 977.9 / 18.02 g/mol= 54.3
moles K+ = 0.438 x 2 = 0.876
moles CrO42- = 0.438
moles ions = 0.876 + 0.438=1.31
mole fraction water = 54.3 / 54.3 + 1.31 =0.976
p = 0.976 x 0.0313 =0.0306 atm