CHEM 1212L-145 Experiment #16: Freezing- Point Depression Prepared by: Long Nguyen 6/18/2013 Instructor: Dr. Malinconico
Introduction: In this experiment, we will use TBA (T- butyl alcohol) to determine the molar mass of an unknown based on the difference in freezing point of TBA and the solution which contains TBA and the unknown. Theoretically, the freezing point of a solution is lower than the freezing point of the solvent that is used to make the solution. For a non-electrolyte solution, the difference in freezing points is calculated as follow: t f = f f m Where m is the molality of the solution, and is define as moles of solute divided by kilograms of solvent. Next, we use this equation to experimentally determine the molality of the solution and obtain the molar mass of the unknown. Molar mass of solute= mass solute/ (m*kg solvent) Goals Students are to determine the molar mass of an unknown using TBA as a solvent. Students are also to plot the freezing point data using excel. Procedure: The procedure was done in the same way as in the lab manual: Block/McKelvy (2012). Laboratory Experiments for Chem 1211L & 1212L Cengage Learning (7th ed.),
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