the freezing point of ethanol (C2H5OH) is -114.6°C.?
The molal freezing point depression constant for ethanol is 2.00°C/m. What is the freezing point (°C) of a solution prepared by dissolving 50.0 g of glycerol (C3H8O3 a nonelectrolyte) in 200 g of ethanol?
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molar mass of glycerol = 92.09 g / mole
in 50.0 g we have 50.0 / 92.09 = 0.5429 moles
which are dissolved in 200g of solvent
so moles per kg of solvent = 0.5429 x 1000 / 200 = 2.715 m
delta T = m x Kf
= 2.715 x 2.00
= 5.43 oC
so the new freezing point = -114.6 - 5.43 = -120oC
-64.6 celsius