Abstract

The purpose of this lab is to understand how intermolecular interactions affect physical properties.  To do this, 50-mL of ethanol is transferred into an Erlenmeyer flask in a water bath.  The water bath has been brought up to 80 degrees C before placing the Erlenmeyer flask in. The ethanol is then brought to a boil and removed from the water bath.  A stopper, holding a pressure and temperature sensor in it, is tightly inserted into the Erlenmeyer flask.  The pressure is observed as the temperature goes down.  Data is recorded until the temperature drops to about 30 degrees C.  The process is then repeated with a 60 degrees C bath and 50-mL of acetone.  The flask should be cooled to about 25 degrees C before stopping the recording of data. The expected results are Ethanol to have lower vapor pressure compared to Acetone, because of Ethanol having greater bond strength, and large molecules compared to the weak bond strength and smaller molecules of Acetone.  Ethanol will then appear to have a higher heat of vaporization than Acetone.  These results are important because it allows the experimenter to know the energy required for a known amount of substance to escape from the liquid to gas phase.