Anonymous
Anonymous asked in Science & MathematicsChemistry · 2 months ago

Chem Homework Question?

Determine freezing point for a solution made by adding 2.0 grams of ethyl alcohol to 25.0

mL of chloroform. The density of chloroform is 1.49 g/mL. 

Nothing I read helps so anything is useful!

Update:

Thank you so much you have no idea how much this means @hcbiochem !

1 Answer

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  • 2 months ago

    You need to know the freezing point depression constant for chloroform, and ultimately, its normal freezing point.

    Calculate the molality of the solution:

    Moles ethanol = 2.0 g / 46.07 g/mol = 0.0434 mol ethanol

    Mass chloroform = 25.0 mL X 1.49 g/mL = 37.25 g

    molality = 0.0434 mol ethanol / 0.03725 kg solvent = 1.165 molal solution

    Kf for chloroform is 4.68 C/m. So:

    Change in freezing point = 4.68 C/m (1.165 m) = 5.45 C

    The normal freezing point of chlroform is -63.5 C. So, the solution will freeze at:

    -63.5 - 5.45 = -69.0 C

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