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18 November, 00:02

The vapor pressure of chloroform is 173.11 mm Hg at 25 °C. A nonvolatile, nonelectrolyte that dissolves in chloroform is aspirin. Calculate the vapor pressure of the solution at 25 °C when 9.322 grams of aspirin, C9H8O4 (180.1 g/mol), are dissolved in 263.4 grams of chloroform. chloroform = CHCl3 = 119.40 g/mol. VP (solution) = mm Hg

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  1. 18 November, 00:27
    0
    VP (solution) = 171.56 mmHg

    Explanation:

    Vapor pressure of pure solvent (P°) - Vapor pressure of solution (P') = P°. Xm

    Let's replace the dа ta:

    173.11 mmHg - P' = 173.11 mmHg. Xm

    Let's determine the Xm (mole fraction for solute)

    Mole fraction for solute = Moles of solute / Total moles

    Total moles = Moles of solute + moles of solvent.

    Let's determine the moles

    Moles of solvent → 623.4 g / 119.4 g/mol = 5.22 moles

    Moles of solute → 9.322 g / 180.1 g/mol = 0.052 moles

    Total moles = 0.052 + 5.22 = 5.272 moles

    Xm = 0.052 moles / 5.272 moles = 0.009 → 9/1000

    173.11 mmHg - P' = 173.11 mmHg. 9/1000

    P' = - (173.11 mmHg. 9/1000 - 173.11 mmHg)

    P' = 171.56 mmHg
  2. 18 November, 00:29
    0
    The vapor pressure of the solution is 169.25 mm Hg

    Explanation:

    Step 1: Data given

    Vapor pressure of pure chloroform at 25 °C = 173.11 mm Hg

    Mass of aspirin = 9.322 grams

    Molar mass of aspirin = 180.1 g/mol

    Mass of chloroform = 263.4 grams

    Molar mass chloroform = 119.40 g/mol

    Step 2: Calculate moles of aspirin

    Moles Aspirin = mass aspirin / molar mass aspirin

    Moles aspirin = 9.322 grams / 180.1 g/mol

    Moles aspirin = 0.05176 moles

    Step 3: Calculate moles of chloroform

    Moles chloroform = 263.4 grams / 119.40 g/mol

    Moles chloroform = 2.206 moles

    Step 4: Calculate mol fraction of chloroform

    Mol fraction chloroform = moles chloroform / total moles

    Mol fraction chloroform = 2.206 moles / (0.05176 + 2.206)

    Mol fraction chloroform = 0.9777

    Mol fraction aspirin = 1 - 0.9777 = 0.0223

    Step 5: Calculate the vapor pressure of the solution

    Vapor pressure solution = Mol fraction chloroform * vapor pressure chloroform

    Vapor pressure solution = 0.9777 * 173.11 mm Hg

    Vapor pressure solution = 169.25 mm Hg

    The vapor pressure of the solution is 169.25 mm Hg
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