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Homework Help: Vapor Pressure and Raoult's Law

  1. Nov 17, 2013 #1


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    1. The problem statement, all variables and given/known data

    The vapor pressure of pure water at 45 degrees C is 71.9 mm Hg. What is the vapor pressure when 18g of sucrose (MM = 342.3g/mol) is added to 82g of water?

    2. Relevant equations

    VP of solution = mole fraction of solvent * VP of pure solvent

    3. The attempt at a solution

    82g of water / (18g/mol) = 4.555... moles of water.

    18g of sucrose / (342.3g/mol) = 0.0525 moles of water

    Mole fraction of solvent (water) = 0.988.

    0.988 * 71.9 mm Hg = new vapor pressure of 71.1 mm Hg.

    Is my work correct? It's 3 AM here and I'm just a bit concerned about how accurate I am in doing these practice problems.
  2. jcsd
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