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Experiment 3Determination of a Molar Mass by Freezing PointDepressionStudent Name: Adam SadowskiStudent Number: 1000142071Other Member(s) of the Team: Kartik MozaPractical Section Number: 0122Date the Experiment was Performed: 01/03/2013Date the Report was Submitted: 08/03/2013Submitted to Dr. I-San Chan
2PurposeMolar mass determination allows for the identification and oftentimes the discovery of an unknown compound; it has contributed to our recognizing over 70 million inorganic and organic substances.2Using the colligative property of freezing-point depression, the molar mass of an unknown, non-volatile solute will be determined. Because the vapor pressure of a solution is always lower than that of its solvent, the temperature at which a solution’s vapor pressure equals that of its solvent (i.e. the freezing point) will be lower when the solution contains a non-volatile solute. The freezing-point depression is proportional to molality, the molal freezing point depression constant and I (the number of particles of solute when in solution):ΔT = i KfmThe freezing point of the pure solvent cyclohexane and of solutions containing cyclohexane with an unknown solute will be found by plotting cooling curves (temperature vs. time).Experimental MethodPreparing of an ice-water bath and the solutions to be contained therein, as well as the