Gas Temperature and Pressure

 

Gases are made up of tiny particles. The particles are in constant motion and exert pressure when they strike the walls of their container. In this simple experiment, you will use a temperature probe, a pressure sensor, and an air sample in a stoppered flask to study the relationship between gas pressure and temperature. The volume and amount of gas will be kept constant. The results will be expressed in words, in a table, with a graph, and with a mathematical equation.

 

OBJECTIVES

In this experiment, you will

  • use a TI Graphing Calculator, a CBL System, and a temperature probe to measure temperature
  • use a TI Graphing Calculator, a CBL System, and a pressure sensor to measure the pressure of an air sample at several different temperatures
  • make a table of the results
  • graph the results
  • predict the pressure at other temperatures
  • describe the relationship between gas pressure and temperature with words and with a mathematical equation
  •  

    MATERIALS

    CBL System
    heavy-wall plastic tubing
    TI Graphing Calculator
    slit stopper
    Vernier Temperature Probe
    125-mL flask
    Vernier Pressure Sensor
    four 1-liter beakers
    2 Vernier adapter cables
    ice
    1-hole stopper fitted with rigid plastic tube
    hot plate
    ring stand and utility clamp
    glove or cloth

    Figure 1

    PROCEDURE

    1.Obtain and wear goggles.

    2.Prepare a boiling-water bath. Put about 800 mL of hot tap water into a l-L beaker and place it on a hot plate. Turn the hot plate to a high setting.

    3.Prepare an ice-water bath. Put about 700 mL of cold tap water into a second 1-L beaker and add ice.

    4.Put about 800 mL of room-temperature water into a third 1-L beaker.

    5.Put about 800 mL of hot tap water into a fourth 1-L beaker.

    6.Prepare the temperature probe and pressure sensor for data collection.

    Figure 3
    figure 2

  • 7.Turn on the CBL unit and the calculator. Press and select PHYSCI. Press , then press again to go to the MAIN MENU.

    8.Set up the calculator and CBL for a temperature probe and calibration (in °C), and a pressure sensor and calibration (in atmospheres).

    9.Set up the calculator and CBL for data collection.

    10.Collect pressure vs. temperature data for your gas sample.

    11.Select MORE DATA on the TRIGGER menu. Repeat the Step 10 procedure using the room-temperature bath.

    12.Select MORE DATA on the TRIGGER menu. Repeat the Step 10 procedure using the hot-water bath.

    13.Collect the boiling-water data.

    14.Record your data.

     

    DATA AND CALCULATIONS

    Water bathTemperaturePressureTemperature

    (°C)(atm)(K)

    Ice__________________

    Room temperature______ ____________

    Hot __________________

    Boiling__________________

     

    PROCESSING THE DATA

    1.Convert the Celsius temperatures (°C) to kelvins (K) and record the results in the last column of the Data and Calculations Table. Use the formula

    K = °C + 273

    For example, 2°C = 275 K (275 K = 2°C + 273).

    2.Graph the data. Plot TEMPERATURE (in K) on the horizontal axis and PRESSURE (in atm) on the vertical axis. Begin both axes with zero (0). Draw in the best-fitting straight line passing through or near your points.

    3.What is the relationship between gas pressure (P) and temperature (T) in words

     

     

    4.Explain this relationship, using the idea of particle speed.

     

     

    5.According to your graph, what would the pressure be at 350 K (77°C) At 200 K (–73°C) At 400 K (127°C)

     

    6.Should the graph go through the origin (0,0) Explain.

     

     

     

    7.Write an equation to express the relationship between pressure and temperature. Use the symbols P, T, and k.

     

     

     

    EXTENSIONS

    1.Use the TI-Graph Link cable and program to transfer your graph image to a Macintosh or IBM-compatible computer. Print a copy of the graph.

    2.Repeat the experiment using a pure, noncorrosive gas, such as oxygen, butane, or carbon dioxide. Compare the results with your results for air.

    3.Do the experiment using a dry-ice and amyl-alcohol bath or a dry-ice and acetone bath to get a temperature of about –78°C (195 K).


    Author Unknown

    Questions? Comments??
    Patrick Gormley, editor