CHEM 103 Lab Report 8 Portage learning

Chemistry Lab Report Experiment #: 8 Title: Molecular Mass Purpose: Estimation by freezing point depression. Procedure: 10.0 mL of cyclohexane is measured; this is the solvent. The cyclohexane is then transferred into a test tube. The test tube is fitted with a special stopper and there is a special hole that has a wire to help stir and is also fitted with a thermometer. The test tube is then inserted into a beaker containing a mixture of ice and salt, this creates a cold bath. The salt is what is used in the wintertime to melt ice on your sidewalks. We let the cyclohexane cool down and freeze and while that is happening, we will stir it a little. We are going to let about half of the cyclohexane freeze. He continues to stir the cyclohexane while it is cooling down and in the process of freezing. The cyclohexane is steadily lowering in temperature from 10, to 8, to 7. The bottom part has formed crystals and is now frozen, the temperature is at 6.6. For the second experiment the solute weighs 0.3014 g and he pulls it out and adds it to the test tube with the solvent. He is shaking the test tube to combine the two, he wants to make sure the solute is completely dissolved. The stopper with the wire and thermometer is then reinserted into the test tube and added back into the ice bath to cool it until it freezes. We will probably see a difference of 5-7°C with the solute added. He is continuing to stir the mixture until it begins to freeze. Data/Results/Calculations: Once we take the cyclohexane out of the ice bath, we are going to put it in a ring stand and let it warm. We are going to take a temperature reading every 30 seconds for a temperature warming plot. 30 seconds: 6.6°C 120 seconds: 7.0°C