Report of a Physical Experiment Essay Example

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Report of a Physical Experiment

Report of a Physical Experiment


The report will deal with the process of verifying the adiabatic gas law using the PASCOTM adiabatic compression chamber. For the purpose of the experiment, argon, nitrogen and carbon dioxide gases will be considered. Analysis of the results will basically rely on the equations of determining the molar specific heat of an ideal gas.

This experiment was carried out to determine the adiabatic gas law as well as establish ۷ for a monatomic, diatomic and polyatomic gas. In the determination of the adiabatic gas law, consideration is given to the molar specific heat capacity of an ideal gas. This is defined as the heat energy needed per mole of a gas for a 1K change in temperature measured in J.mol-1.K-1. In this experiment, three different gases were used to verify the adiabatic gas law (Chang, 2000).

The following equation is important in the determination of molar specific heat:


These included argon, carbon dioxide and nitrogen gases. For the purpose of this experiment, the following setup was used to get the results that were ultimately analyzed.

Professor: 1

In the above setup, the basis was on the PASCOTM adiabatic compression chamber (Ambaum, 2010). A close look at the diagram reveals that a piston of acetal plastic is driven upwards or downwards in an acrylic cylinder through manual movements. On the opposite sides of the piton, two brass gas valves have been placed for the purpose of introducing pure CO2, Ar and N2. So as the system can be evacuated prior to the introduction of the gases, a dual-stage roughing pump was incorporated. On the other hand, there was need for monitoring of the position of the piston and this was facilitated through the use of a linear potential driver. Eventually, a voltage source was applied across the potentiometer element (Chang, 2005). This facilitated the voltage from the commutator brush to show the position of the piston and therefore the volume of the confined gas was determined. For effective readings to be taken a transparent millimeter scale was used on the front of the cylinder and hence initial and final readings of the gas volume were noted.

Individual gases were then introduced by connecting a tube on one of the three bottles to the user pressure gauge as indicated in the figure above. At the same time, ensure that main gas valves on the gas bottle are closed before opening the compression cylinder and the user gauge. After readings were taken on the volume of the gas, graphs of pressure vs. volume as well as temperature vs. volume were plotted as indicated in the graphs below (Ambaum, 2010).

Professor: 2

Carbon Dioxide

Professor: 3


Professor: 4

As indicated in the graphs, it is notable that data was plotted in log/log format so that it could be easy to verify the equation:

Professor: 5

In this case, ۷ = CP/CV as indicated before. The relationship can be shown on the graph as below.

Professor: 6

The shaded region in the graph shows the work done during compression as pressure was being exerted to the gas. The adiabatic law can eventually be calculated using the following equation.

Professor: 7

The above equation is therefore important in the determination of ۷ in the process of adiabatic compression. Adiabatic in this case refers to the process in which the gas compression occurs without thermal energy affecting the system through entering or leaving (Moore, 2002). From the graphs therefore, calculations were done and corresponding values of ۷ were determined as shown in the tables below. These values were used ultimately in the determination of the adiabatic gas law as indicated in the graphs above.

To find ۷:-


To find w:-


V1= 1.376×10-4

V2= 1.848×10-4

Therefore w=0.1742 or 0.1727

V1= 1.184×10-4


Therefore w=0.1680 or 0.1673



Therefore w=0.1127 or 0.1131

In conclusion, the report has focused on the adiabatic law which has been verified using three gases: Argon, Carbon dioxide and Nitrogen gases. As seen in the report, the PASCOTM adiabatic compression chamber was utilized in compressing the individual gases for the analysis of the results found. It has also been noted that the molar specific heat of an ideal gas is paramount in the determination of the adiabatic gas law.


Moore, T. (2002). Six ideas that shaped physics: Some processes are irreversible. New York: McGraw-Hill.

Ambaum, M. (2010). Thermal Physics of the Atmosphere. California: John Wiley and Sons.

Chang, R. (2005). Physical chemistry for the biosciences. London: University Science Books.

Chang, R. (2000). Physical chemistry for the chemical and biological sciences. London: University Science Books.