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

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