1、Name _ Class _ Date _C06 1999 PASCO scientific p. 33Activity C06: Determine the Vapor Pressure of a Compound (Pressure, Temperature Sensors)Concept DataStudio ScienceWorkshop (Mac) ScienceWorkshop (Win)Phase change C06 Vapor Pressure.DS C06 Determine Vapor Pressure C06_VAPO.SWSEquipment Needed Qty E
2、quipment Needed QtyPressure Sensor (CI-6532A) 1 Thermometer (SE-9084) 1Temperature Sensor (CI-6505A) 1 Tubing, plastic (w/sensor) 1Beaker, 400 mL 2 Protective gear PSConnector, rubber stopper (w/sensor) 1Coupling, quick release (w/sensor) 1 Chemicals and Consumables QtyFlask, 250 mL 1 Acetone 10 mLG
3、raduated cylinder 1 Ethanol 10 mLHot plate 1 Glycerin 1 mLRubber stopper, two-hole 1 Water 1 LWhat Do You Think?How does the vapor pressure of a pure liquid change as the temperature of the liquid changes? Will the type of liquid have an effect on the rate of change of the vapor pressure as the temp
4、erature changes?Take time to answer the What Do You Think? question(s) in the Lab Report section.BackgroundMost substances have characteristic melting and boiling points at a given pressure. If the temperature of the surroundings is higher than the temperature of the substance, the surroundings give
5、 thermal energy to the molecules of matter that make up the substance. The thermal energy causes the molecules to rotate (spin), vibrate and translate (move from place to place). The intermolecular forces of attraction that hold the molecules of a substance together are strained by an increase in an
6、y movement of the molecules. Strong intermolecular forces of attraction are more difficult to break and as a result require a higher temperature to cause molecular movement.The higher the temperature of a liquid, the greater the average kinetic energy of the molecules. When the molecules of solid ma
7、tter absorb enough energy, the substance melts and forms a liquid. When liquid matter absorbs enough energy, the molecules move with enough speed and momentum to separate from each other and escape into the vapor or gas phase. As more and more molecules break from the liquid state into the vapor or
8、gaseous state, the pressure they exert increases in a closed Chemistry Labs with Computers Student WorkbookC06: Determine Vapor Pressure 012-07055A p. 34 1999 PASCO scientific C06system. This is the vapor pressure of a liquid. The vapor pressure of all liquids is directly related to the temperature
9、of the liquid.Name _ Class _ Date _C06 1999 PASCO scientific p. 35SAFETY REMINDERS Wear protective gear. Follow directions for using the equipment. Dispose of all chemicals and solutions properly.SAFETY ALERTKeep flammable substances away from flames.For You To DoUse the Pressure Sensor to measure t
10、he vapor pressure of the liquid inside a flask. Use the Temperature Sensor to measure the temperature of the liquid. Use DataStudio or ScienceWorkshop to record and display the data.PART I: Computer Setup1. Connect the ScienceWorkshop interface to the computer, turn on the interface, and turn on the
11、 computer. 2. Connect the DIN plug of the Temperature Sensor into Analog Channel A of the interface. Connect the DIN plug of the Pressure Sensor into Analog Channel B of the interface.3. Open the file titled as shown;DataStudio ScienceWorkshop (Mac) ScienceWorkshop (Win)C06 Vapor Pressure.DS C06 Det
12、ermine Vapor Pressure C06_VAPO.SWS The DataStudio file has a Workbook display. Read the instructions in the Workbook. The ScienceWorkshop file has a Graph display with a plot of Temperature versus Time and a plot of Pressure versus Time. Data recording is set for ten measurements per second (10 Hz).
13、Chemistry Labs with Computers Student WorkbookC06: Determine Vapor Pressure 012-07055A p. 36 1999 PASCO scientific C06PART II: Sensor Calibration and Equipment SetupYou do not need to calibrate the sensors.Set Up Two Water Baths1. Set up a cool water bath. Half fill one beaker with cool water. 2. Se
14、t up a warm water bath. Half fill a second beaker with water and place the beaker on the hot plate. Start heating the second water bath to a temperature of 60 C. Use the thermometer to check the temperature occasionally as you set up the rest of the equipment.Set Up the Equipment1. Put a drop of gly
15、cerin on the barb end of the quick-release coupling and insert the barb into one end of the plastic tubing.2. Put a drop of glycerin on the smaller diameter end of the coupling that will go into the rubber stopper. Insert the small diameter end into the plastic tubing. 3. Put a drop of glycerin on t
16、he larger diameter end of the connector that will go into the rubber stopper, and insert the end into one of the holes in the rubber stopper. 4. Place a drop of glycerin in the other hole of the rubber stopper. Slide the Temperature Sensor through the hole in the rubber stopper. NOTE: Do not put the
17、 rubber stopper into the flask yet.5. Put 10 mL of acetone in the flask. Hold the flask in the hot water bath. 6. Leave the flask in the water bath for four minutes to allow the acetone to vaporize and purge air from the flask.Name _ Class _ Date _C06 1999 PASCO scientific p. 37PART IIIA: Data Recor
18、ding - Acetone1. Place the two hole stopper firmly into the top of the flask with the acetone. Adjust the Temperature Sensor in the rubber stopper so the tip of the sensor is in the liquid. 2. Align the quick-release connector on the end of the plastic tubing with the connector on the pressure port
19、of the Pressure Sensor. Push the connector onto the port, and then turn the connector clockwise until it clicks (about one-eighth turn). 3. Remove the flask from the water bath. 4. Start recording data. (Hint: In DataStudio, click Start ( ). In ScienceWorkshop, click REC ( ).)5. Observe the change i
20、n temperature and pressure as the flask cools.What do you expect the temperature vs. time and the pressure vs. time graphs will look like?6. After four minutes immerse the flask in the cool water bath. 7. Continue recording data until the temperature reaches about 30 C. (Hint: Click Stop to end the
21、data recording.) 8. Slowly remove the two hole stopper to allow air to enter the flask.9. Dispose of the remaining acetone by rinsing the acetone down the drain with a large volume of water following. Rinse and dry the flask.Chemistry Labs with Computers Student WorkbookC06: Determine Vapor Pressure
22、 012-07055A p. 38 1999 PASCO scientific C06PART IIIB: Data Recording - Ethanol1. Heat the hot water bath to 75 C. 2. Put 10 mL of ethanol in the flask. Hold the flask in the hot water bath. 3. Leave the flask in the water bath for four minutes to allow the ethanol to vaporize and purge air from the
23、flask.4. Place the two hole stopper firmly into the top of the flask with the ethanol. Adjust the Temperature Sensor in the rubber stopper so the tip of the sensor is in the liquid. 5. Repeat the data recording procedure for the ethanol.How will the graphs for ethanol differ from the graphs for acet
24、one?Analyzing the Data1. Set up your Graph display to show the data for acetone and for ethanol. (Hint: Rescale the Graph to the data if necessary.)2. Use the Graph display to determine the relationship between pressure and temperature for the two liquids. (Hint: In ScienceWorkshop, change the Graph
25、 display to show Pressure on the vertical axis versus Temperature on the horizontal axis. Click on the “Input” menu button ( ) for the vertical axis of the temperature plot of the Graph. Select “Delete Input” from the Input menu for the temperature plot. Click on the “Input” menu button ( ) for the
26、horizontal axis of the Graph. Select “Analog A, Temp” from the Input menu for the horizontal axis.Name _ Class _ Date _C06 1999 PASCO scientific p. 39 (Click on the “Autoscale” button ( ) to rescale the Graph to the data if necessary.)Use your observations to help you answer the questions in the Lab
27、 Report section.Chemistry Labs with Computers Student WorkbookC06: Determine Vapor Pressure 012-07055A p. 40 1999 PASCO scientific C06Lab Report - Activity C06: Determine the Vapor Pressure of a CompoundWhat Do You Think?How does the vapor pressure of a pure liquid change as the temperature of the l
28、iquid changes? Will the type of liquid have an effect on the rate of change of the vapor pressure as the temperature changes?Questions1. What is the general relationship between the vapor pressure of acetone and the temperature of the liquid?2. Is the relationship linear? Why or why not?3. What is t
29、he general relationship between the vapor pressure of ethanol and the temperature of the liquid?4. Is the relationship between acetone and temperature and ethanol and temperature the same? How are they different?5. Which would you predict has the higher boiling point, acetone or ethanol? Clearly sta
30、te your reasons.6. From the results of your experiment which liquid, acetone or ethanol, has the stronger intermolecular forces of attraction. Clearly state your reasons.Name _ Class _ Date _C06 1999 PASCO scientific p. 417. Using what you learned in this experiment, sketch the pressure vs. temperature for methanol, water, and methane.
