Problem: 0.1 liters of a diatomic gas (y=1.4) undergoes a thermodynamic cycle. The gas is initially at a pressure of 1 atm and has a temperature of 27 degree C. First the gas is heated isovolumetrically to increase its pressure to 3atm, it is then allowed to expand adiabatically until its pressure drops to 2atm, then the gas is reheated isothermally and finally the gas is returned to its original state via an isobaric process. Results Table for Question e:
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ΔU(J) |
ΔQ(J) |
ΔW(J) |
| A→B |
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| B→C |
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| C→D |
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| D→A |
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P(atm) |
V(cm3) |
T(K) |
| A |
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| B |
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| C |
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| D |
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Questions: a) Explain the concept of a system and identify the components and type of the system you have chosen to analyze for the problem given.
b) Draw a clearly labeled PV diagram for the process. Label the initial state ''A'' and subsequent states ''B'',''C'', and ''D''.
c) Which thermodynamic state variable remains constant throughout the process? Determine the value of this variable.
d) Complete the missing information in the tables above showing all working and explanations on a separate sheet. No marks will be given if the working or explanations for your results cannot be identified. Number the equations in your working and cross- reference with each result inserted into the tables above.
e) What is the net work done by the gas during the cycle?
f) What is the net change in internal energy of the gas per complete cycle ? Is this the result you expect?