NAME: Post-Lab Assignment Experiment 18 1. Is the density of a compound a collig

Question

NAME: Post-Lab Assignment Experiment 18 1. Is the density of a compound a colligative property? Why or why not? 2. While calibrating the temperature sensor, a student carelessly wrote down the wrong observed performed the of pure -2.5°C than the true reading of -5°C. The student the same) on rest of the experiment accurately. this single effect or the following values igh, low, and justify your answers. a. Kf of water b. ATf of the unknown solution c. Molality of the unknown solution d. Mass of the unknown compound e. Molar mass of the unknown compound A colligative property to freezing point depressing is boiling point elevation. In this corollary case, a solution will begin to boil at a higher temperature than its corresponding pure solvent from the following equation: Here, AT is the change in boiling point, Ko is the molal boiling point elevation constant individual to the solvent, and m is the solution's concentration in units of molality Answer the following questions about boiling point elevation. 18-6

Explanation / Answer

Freezing point depression= i*kf*m, m= molality, Kf= freezing point depression constant i= Van't Hoff factor

When the freezing point is at -2.5 deg.c where as actually, the freezing point is -5 deg.c

Freezing point = freezing point of water- Freezing point depression

Freezing point depression=0 +2.5= 2.5 deg.c ( measured)

Actual freezing point depression= 5 deg.c

There is an increase in freezing point depression. This results in large Kf, large molality.

molality= moles/ kg of solvent

molality= mass/ molar mass/ kg of solvent

mass of unknown compound will be more, molar mass will be less.

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