PASCO TD-8565, Instruction Manual And Experiment Manual, Page: 28 / 75

012-05110C Adiabatic Gas Law Apparatus
9
EQUIPMENT NEEDED: Optional:
– Adiabatic Gas Law Apparatus, -Monatomic, Diatomic,
– Series 6500 Computer Interface.
and Polyatomic Gases.
Purpose
The purpose of this experiment is to show
P
1
V
1
γ
= P
2
V
2
γ
and
T
1
V
1
(
γ
–1)
= T
2
V
2
(
γ
–1)
, To
determine the value of Gamma, and to measure the amount of work done to compress a
gas adiabatically.
Theory
In this experiment a gas confined in the cylinder is compressed so rapidly that there is only
sufficient time for a small quantity of thermal energy to escape the gas. For this reason the
process is almost adiabatic. The more rapidly the volume is changed the closer the process
approaches being adiabatic.
➤
NOTE
: The response times of the pressure and volume transducers are negligibly short.
However the unavoidable thermal inertia of the temperature sensor causes the
temperature measurement to lag by 30-50 ms.
A complete experiment would include the study of gases having different structures
including monatomic argon, diatomic air or nitrogen, and triatomic carbon dioxide.
Procedure
➀ Select a gas to compress, (Air is a good gas to start with).
➁ If you are using a gas other than air, purge the cylinder in the following manner:
a. Connect the gas supply to one of the gas cocks.
➤
NOTE:
The pressure should be less than 35 kPa or 5 PSI.This prevents damage
from the external gas cylinder or supply to the temperature sensor. The flow of gas
must be kept at a low level to avoid breaking the wire or the sensor.
b. Remove the piston excursion limit pins so the range of volumes is maximum
(approximately 16 to 6).
c. With the piston down and the second gas cock closed, fill the cylinder to maximum
volume with the gas.
d. Now shut the incoming gas cock off and exhaust through the second gas cock.
e. Close the exhaust cock and re-fill with gas.
Repeat this process at least nine more times, ending with a full cylinder. Shut both gas
cocks before performing the experiments. If during the experiment some gas escapes
simply add more.
Experiment: Measurement of Work to Compress
Gases Adiabatically