CHEM Molar Mass Determination CHEM Molar Mass Determination Objectives: Molar Masses of some Nonelectrolytes 1. To introduce colligative properties of solutions 2. To determine the freuzing point liquids 3. To use experimental freezing point depression data to calculate the molar mass of an unknown nonelectrolyte solute Calculations: Show all your work on your Lab Report Sheat. 1. Plot temperature versus time on the same graph paper for both the solvent (P art I) and the solution (Part II.) 2. Determine the change in freazing point, Ta from the graph. Refer to the graph below: Sample Calculations: In an experiment similar to the one you are perforning here, 3.50g of an Freezing-Point Depression and Molar Mass unknown nonelectroly te was dissolved in 20.0mL of water (density =1.00 g/mL).Ti was graphically determine d to be 1.81c. Calculate the molar mass of the unknown and identify it. (K, of water =1.86C/m) 1. molality (m) of the solution: Ti=iKym;i=1 (nonelectrolyte) m=1KfTfm=11.86C/m1.81Cm=0.973mol/kgofsolvent 3. Determine the molar mass of your unknown compound (density of water = 2. moles of solute 1.00g/mL ). a. Molality of unknown solute, m=TKK. b. Moles of unknown solute =mkg of water c. Molar mass of unknown solute = mass of unknown solute moles of unknown solute kg of solvent =( density of water 20.0mL)/1000mL =(1.00g/mL20.0mL)/1000mL =2.00102kg 4. Identify the unknown from the possibilities in the table below. moles of solute =0.973mol/kg(2.00102kg) =1.95102mol CHEM Molar Mass Determination Online CHEM 1412 Molar Mass Determination 3. molar mass of the unknown solute molarmass=molesofunknowngofunknown=1.95102mol3.50g=180.g/mol Molar Mass Determination Lab Report Sheet PART I: FP of the Solvent PART II: FP of the Solution The unknown solute is: gbucose. Fill in the excel tables with your data and the graph will generate automatically. Online CHEM 1412 Molar Mass Determination Online CHEM 1412 Molar Mass Determination Results Table Conclusion