Work to compress a gas (constant external pressure)

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SUMMARY

The work done to compress a gas under constant external pressure is calculated using the formula w = -P(ext)ΔV. This equation applies equally to both gas expansion and compression scenarios. In a comparison of two gases compressed to the same final volume, one at 10 atm and the other at 5 atm, the work done on the gas at 10 atm is indeed double that of the gas at 5 atm, highlighting the direct relationship between external pressure and work. The discussion confirms that while the sign of ΔV changes, the fundamental principles governing work remain consistent across both processes.

PREREQUISITES
  • Understanding of thermodynamic principles
  • Familiarity with the ideal gas law
  • Knowledge of pressure-volume work calculations
  • Basic grasp of the concepts of internal and external pressure
NEXT STEPS
  • Study the implications of the ideal gas law on work calculations
  • Explore the differences between isothermal and adiabatic processes
  • Learn about the relationship between pressure, volume, and temperature in gas behavior
  • Investigate real gas behavior and deviations from ideal gas assumptions
USEFUL FOR

Students of thermodynamics, chemical engineers, and professionals involved in gas compression processes will benefit from this discussion.

1drdan
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What is the work to compress a gas under constant external pressure?
It seems that it is supposed to be w = -P(ext)delta(V)
This equation is certainly true for expansion of a gas, is it also true for compression?
So if we have two gases, same initial conditions, same delta(v) under compression. One is compressed by 10 atm and the other by 5 atm. They end at the same volume, but have different work done on them?
The observational difference I can see is that the 10 atm compression would occur faster than the 5 atm compression. Is the work really a factor of 2 different?
Or, is work really dependent upon the lower of internal and external pressures, and the books talk about expansion more than compression?
 
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Yes, it's the same concept, only the sign of delta(V) changes depending on the situation.
 

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