Freezing point calculations question

Question

If the freezing point of a molal solution of a nonelectrolyte is -1.86°C, what is the freezing point of a 10% aqueous solution of dextrose (m.w. 180)? (Assume that the volume of the molal solution is approximately 1 liter)?

Answer: -1.03 degrees C

 

Please show how exactly this answer is correct

 

Answer 1

If we assume the linearity of the depression-concentration relationship, we can use the simple ΔT_F = K_F · m · i equation.

Assuming that the solvent is the same in both cases, you can find the cryoscopic constant from the solvent from the first set of data and use it to solve the question (remembering to convert the 10% by weight concentration into molality).

 

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