Can I find molarity in this problem?

Posted on 2016-02-16 17:06:00 in Chemistry by MAK

Teacher wanted to save time in lab and premixed unknown solution for Colligative lab. 

I know that the unknown solution freezes at -5℃, it was tested several times. I know that the solvent is water. so Kf is 1.853℃/m 
I believe that the ΔTf is 5℃ (solvent - solution or 0-(-5) =5℃) 

I know that my solution was 5ml. 

Now the questions are: 
Freezing point of water: 0℃ 
Freezing point of solution: -5.0℃ 
Freezing point depression: 5.0℃ 
Determine the molarity of the solution: 
Show equation used: 
I was going to use the formula 
ΔTf = Kf · x · m which gives me 
5.0℃ = 1.853 ℃·kg/m · x · m 
I might be able to solve for molality but how can I solve for molarity of the solution when I was given a solution of unknown ration between water and something else? Is this even solvable? I only know that I have 5mL of a solution that freezes at -5.0℃, water is the solvent.

How many moles of solute in 1.00kg of solvent? 

How many gram of water do you use in this case? Calculate the number of moles based on the amount of water you use. 

Calculate the molecular weight of the unknown compound (gram/mol)

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