What is the molecular weight of glucose if 22.5grams of glucose gives a frezing pnt oF–0.93°C when dissolved..

What is the molecular weight of glucose if 22.5 grams of glucose gives a freezing point oF–0.93°C when dissolved in 250 g water?

Answer:
The freezing point lowering is characteristic of the solvent and is directly proportional to the molal concentration of dissolved particles in the solution.
Kf for H2O = 1.86

delta T = m x kf
m = delta T / kf = 0.93 / 1.86 = 0.5

The solution is 0.5 m

m = moles / Kg solvent

0.5 = moles / 0.250

moles = 0.5 x 0.250 = 0.125

Molecular weight = 22.5 / 0.125 = 180 g/mol
C6H12O6
6(12)+1(1)+6(16)
72+1+36
109

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