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ID: 804989 • Letter: P

Question

Please include an answer and a thorough explanation for full points, thank you!

A solution contains 4.00 g of unknown solute and 96.00 g of water. The solution freezing point is -0.229 degree C and the freezing point of pure water is 0 degree C. calculate the molality given that the Kr of water is 1.86 degree C/m. PLEASE ROUND TO 3 SIGNIFICANT FIGURES FOR YOUR FINAL ANSWER AND DO NOT USE SCIENTIFIC NOTATION!!! DO NOT INCLUDE UNITS! calculate the molar mass (in g/mol) of the unknown solute using the answer and information in the previous section. PLEASE ROUND TO 3 SIGNIFICANT FIGURES FOR YOUR FINAL ANSWER AND DO NOT USE SCIENTIFIC NOTATION!!! DO NOT INCLUDE UNITS!

Explanation / Answer

Assuming the solute does not break down into ions,

a)Depression in freezing point=Kf*b=0.229

1.86*b=0.229

b=0.123 mol/kg water

b)Let M be the molar mass.

Molality=(4/M)/0.096=0.123

M=338g/mol