Gas Laws Demonstrator, 52-2088
This Gas Laws Demonstrator is ideal for physics courses in high schools. It can
demonstrate Boyle-Mariotte’s law, Charles’s law, Gay-Lussac’s law and the ideal gas
law equation.
1. Structure and principle
This demonstrator consists of a gas tube, manometer, constant volume chambers,
fixed frame and volume scale. As shown, the gas tube is divided into two parts of
outer tube and pipe plug. There are several little holes in friction surface in the pipe
plug and with a thin glass tube through both ends. The upper is connected to the
manometer, the bottom is connected to the gas that will be tested, but it is not
connected with the interior of the pipe plug. The pipe plug is filled with special oil. The
oil level is about 5mm higher than the little holes in middle.
A little oil will be pulled out while the pipe plug is slid, to keep the contact surface
smooth and increase the air tightness.
The volume and pressure of the gas can be read from the volume scale on the
manometer. The volume can be changed by pressing or pulling the pipe plug. The
rotating pointer of the manometer indicates the change in pressure. It demonstrates
the relationship between pressure ‘P’ and volume ‘V’ at the same temperature
(Boyle-Mariotte law). The temperature of the gas can be changed by dipping the gas
tube into a beaker filled with hot water. This can demonstrate the relationship between
pressure ‘P’, volume ‘V’ and temperature ‘T’ (Ideal gas law). By keeping the volume ‘V’
and pressure ‘P’ unchanged, it can demonstrate Charles’s law or Gay-Lussac’s law.
2. Experimental methods and procedure
Fix the demonstrator on to the square support. Open the rubber cap in the bottom of
gas tube and move the pipe plug several times by hand to coat the oil evenly over the
contact surfaces of the pipe plug and the outside tube.
You will require the demonstrator, an 800ml beaker, a thermometer and some hot
water.
1/ Demonstration of Boyle-Mariotte’s law.
Slide the pipe plug to make the gas volume V0 = 2 units of volume. Tighten the nut of
the constant volume chambers and push on the rubber cap. The pressure of the gas
is P0 = 1x 105Pa at this moment.
Loosen the nut of the constant volume chambers and pull or push the pipe plug by
hand to vary the volume of gas and note V1, V2, etc. and the corresponding pressure
P1, P2, etc., shown on the manometer. The results show that there is a relationship
between P and V within allowable error, thus verifying Boyle-Mariotte’s law.
V
P（×105Pa）
P·V
Example results:
2
1
1.0
2.0
2.0
2.0
4
0.50
2.0
3
0.67
2.01
2/ Demonstration of Charles’s law
Slide the pipe plug to make the gas volume V0 = 2 units of volume. Tighten the nut of
the constant volume chambers and push on the rubber cap. The pressure of the gas
is P0 = 1x 105Pa at this moment. Loosen the screw of the fixed frame and dip the glass
tube and the thermometer into the beaker which is filled with hot water (Ensure that
the water level is higher than scale ‘4’).
The temperature and pressure of the gas will rise. After 2 to 3 minutes, the gas
temperature and water temperature will be in equilibrium, write down the pressure P1
and temperature T1.
Change the water temperature several times and repeat the experiment to get several
different values of T and P.
Finally, the results show that in the same volume, the ratio of pressure and
temperature for the gas is a constant within allowable error, thus verifying Charles’s
law.
V
2
Example results
T=273+
P
1
（ ×105)
301
1.0
331
1.1
352
1.3
P
T
0.0033
0.0033
0.0033
3/ Demonstration of Gay-Lussac’s law
Slide the pipe plug to make the gas volume V0 = 2 units of volume. Loosen the nut of
the constant volume chambers. The pressure of the gas is P0 = 1x 105Pa at this
moment. Make a note of the pressure, volume and temperature. Loosen the screw of
the fixed frame and dip the glass tube and the thermometer into the beaker which is
filled with hot water (Ensure that the water level is higher than scale ‘4’).
The temperature and volume of the gas will rise. After 2 to 3 minutes, the gas
temperature and water temperature will be in equilibrium, write down the pressure P1,
volume V1 and temperature T1.
Change the water temperature several times and repeat the experiment to get several
different values of T, V and P.
Finally, the results show that in the same volume, the ratio of pressure and
temperature for the gas is a constant within allowable error, thus verifying
Gay-Lussac’s law.
5
P（ ×10 Pa）
1
Example results:
T=273+t
V
301
2.0
331
2.25
352
2.26
V/T
0.0066
0.0068
0.0074
4/ Demonstration of the equation of the ideal gas law
Slide the pipe plug to make the gas volume V0 = 2 units of volume. Loosen the nut of
the constant volume chambers. The pressure of the gas is P0 = 1x 105Pa at this
moment. Make a note of the pressure, volume and temperature
Dip the glass tube and thermometer into hot water. After the gas temperature and
water temperature have stabilized, note down T1, then move the pipe plug to change
the gas volume to 1 unit. Note down the pressure P1.
Change the water temperature and repeat the experiment to get other values of T2,
V2, P2, etc.
The results show that P x V/T is a constant within allowable error, thus verifying the
ideal gas law equation.
Example results:
T=273+t
V
P( ×105Pa）
V/T
301
2.0
1.0
0.0066
331
2.5
0.95
0.0072
352
1.5
1.6
0.0068
3. Notes
1. Keep the friction surface of the gas tube clean. The oil must be clean and
without impurities. Do not use without oil, the friction and air leakage will
increase sharply.
2. When dipping the gas tube into the hot water, the reading of the thermometer
should be noted after 2 to 3 minutes.
3. The temperature change should be between 10 to 30°C for each repetition of
the experiment. This will make the change of volume and pressure more
obvious.
4. Don’t hold the gas tube during the Boyle-Mariotte law experiment as your hand
will warm it.
5. Dry the demonstrator unit after the experiment and before storing.
Key to parts
1 Rubber cap 2 Outside tube
5 Fixed frame 6 Connector
3 Volume scale 4 Pipe plug
7 Manometer
Version 1, 6May14