An aqueous solution containing 36.9g...

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An aqueous solution containing 36.9 {\rm g} of an unknown molecular (nonelectrolyte) compound in 156.9 {\rm g} of water was found to have a freezing point of -1.4^\circ {\rm C}.

asked Jun 21, 2012 in General Chemistry by kistnus ~Expert~ (614 points)
    

1 Answer

+1 vote
delta T = i x m x kf

i = 1 since it's a nonelectrolyte compound.

Kf water = 1.86 degrees celcius/molality

Plug and Chug:

1.4 = 1 x m x 1.86

m = 0.753mol / 1kg of water

mol = (0.753mol/1kg of water) x 0.1572 = 0.118mol solute

molar mass = 36.9 g/ 0.118 mol=312.46 g/mol
answered Jun 21, 2012 by kistnus ~Expert~ (614 points)

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