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!
Thank you so much you have no idea how much this means @hcbiochem !
- hcbiochemLv 72 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