Determining molar mass by freezing point depression lab

[kevin0788]

Im doing my chemistry lab and ran into trouble with this problem. I am not even where to start or what formulas to use. Any ideas? Thanks.

Suppose that a student calculated Kf of biphenyl to be 81.2 C kg/mol. Calculate the molar mass of an unknown if a solution containing 1.64g of an unknown in 18.22 g of biphenyl froze at 39.9 C

 

[Borek]

What was freezing point depression? What was molality of unknown substance? What is molality definition and how does it depend on the molar mass of the substance?

Note: template provided is to help you organize your knowledge. Basically if you would think what to put into "relevant equation" section you would have to answer questions that I have just posted. So in the future don't ignore the template, put some effort into using it and you will find you know how to solve many questions by yourself.

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