solution exercises

Feb 2015
2
0
20.0 gr C12H22O11 and NaCl are mixed together to form a solution, which is dissolved in 1 kg water. Its freezing point is -0.426 degree celcius. The solution formed is ideal. Find the mass percentage of sucrose in the primary solution, and the molar fraction of sucrose in the primary solution.

First, I found the molality of the solution formed, then, I calculated its molar mass, but in order to find the percentage in mass, I need the mass of the sucrose, since in the beginning its mass is added to the NaCl, 20.0 gr in total.

Please, anyone who can help, I'd appreciate it!
 
May 2010
491
8
freezing point depression

delta T Celsius=I*Kf*m
calculate delta for sugar alone
calculate the salt required to bring the solution to specified depression
you will then have theinfo to calculate mass or mol fractions of the two solutes