Vapor Pressure and Intermolecular Forces
Purpose To observe the change in the vapor pressure of a liquid as the temperature varies.
This information will then be related to the strength of intermolecular forces.
Materials
Measurement PASPORT Xplorer GLX (2) PASPORT Chemistry Sensor (with coupling, tubing, connector)
graduated cylinder stainless steel temperature probe (with sleeve)
Hardware hot plate rubber stopper (size 6), two-hole
beaker, 400-mL flask, 250-mL (2)
Chemicals acetone, 10mL ethanol, 10mL
glycerin, 1mL tap water, 1L
Safety Always work in an area that is well ventilated.
Wear safety glasses and follow standard laboratory safety procedures.
Procedure
Equipment Setup
Cool Water Bath A cool water bath was prepared by half filling one large beaker with cool tap water.
Warm Water Bath A warm water bath was prepared by half filling a second large beaker with hot (75°C) tap water.
The temperature was occasionally monitored using a quick response temperature probe as the rest
of the equipment was prepared.
Tubing and GLX The quick-release coupling and the connector pieces were connected to the tubing
and the tubing was connected to the Chemistry Sensor by the quick-release coupling.
The Chemistry Sensor was connected to port #1 of the GLX datalogger.
Stopper A drop of glycerin was placed on the large end of the connector and one on a hole in
the stopper. The large-diameter end of the connector was inserted securely into the
stopper.
A drop of glycerin in the other hole of the rubber stopper.
The blue plastic tubing was palced on the Temperature probe and the probe was
inserted securely through the hole in the rubber stopper.
The stainless steel temperature probe was connected to the stereo plug on the Chemistry Sensor.
Xplorer GLX From the Home screen the F1 button was pressed to open the Graph Display.
The y-axis was set to Absolute Pressure the x axis was set to Temperature
Record Data
żð 10 mL of acetone was measured using a 10 mL graduated cylinder and placed in the flask. The flask was placed in
the hot water bath and left there for four minutes to allow the acetone to vaporize and purge air from the flask.
żð The two hole stopper was twisted firmly into the top of the flask containing the acetone. The Temperature probe was
adjusted in the rubber stopper so the tip of the probe was in the liquid.
żð The flask was removed from the water bath and the record button was pressed to begin recording data.
żð The change in temperature and pressure was observed as the flask cooled.
żð After four minutes the flask was immersed in the cool water bath and data recording was continued until the
temperature reached about 30°C. The record button was pressed again to end data recording.
żð The two hole stopper was slowly twisted and removed to allow air to enter the flask.
żð The remaining acetone was placed in the organic waste container and the flask was rinsed and dried.
żð The same procedure was followed using 10 mL of ethanol.