Isothermal Compression/Expansion

  • Thread starter opprobe
  • Start date
  • Tags
    Isothermal
In summary, the conversation discusses an isothermal process in which the volume and pressure of a gas change. The equation of state for the gas is given, and the amount of work is calculated using the equations W=-∫P(V)dV and ΔU=Q+W. The solution involves integrating PdV by parts.
  • #1
opprobe
17
0

Homework Statement


Gas obeys Equation of State, PV=RT/(1-bP), where b is a temperature dependent constant.
Isothermal process (T is constant)
V goes from V1 to V2
P goes from P1 to P2

Show that the amount of Work is
W=(P1V1-P2V2)+RTln[(P22V2)/(P12V1)

Homework Equations


W=-∫P(V)dV
ΔU=Q+W

The Attempt at a Solution


Solved PV=RT/(1-bP) for P in terms of V
P=(-1[itex]\pm[/itex]Sqrt[1-4bRT/V])/(2b)

I don't know how to really integrate that expression. I used Wolfram to eventually get this expression:

∫P(V)dV=-V/(2b)[itex]\pm[/itex]RTln(2V(Sqrt[1-4bRT/V]+1)-4bRT)-V*Sqrt[1-4bRT/V]

I'm pretty sure that this isn't the approach to solve this problem. Can someone point me in the right direction?

Thanks in advance!
 
Physics news on Phys.org
  • #2
Try integrating PdV by parts.

Chet
 
  • #3
That did it. Thanks for the help!
 

1. What is isothermal compression/expansion?

Isothermal compression/expansion is a thermodynamic process in which a gas is compressed or expanded while its temperature remains constant. This means that the amount of heat in the system stays the same during the compression/expansion.

2. How is isothermal compression/expansion different from adiabatic compression/expansion?

In isothermal compression/expansion, the temperature of the gas remains constant, while in adiabatic compression/expansion, the temperature changes due to the transfer of heat in or out of the system. This means that in isothermal compression/expansion, the gas does not gain or lose heat, while in adiabatic compression/expansion, the gas may gain or lose heat.

3. What is the ideal gas law and how is it related to isothermal compression/expansion?

The ideal gas law is a mathematical relationship between the pressure, volume, and temperature of a gas. It states that the product of pressure and volume is directly proportional to the temperature and the number of moles of gas. This law is applicable to ideal gases, which behave according to the principles of isothermal compression/expansion.

4. Why is isothermal compression/expansion important in thermodynamics?

Isothermal compression/expansion is important in thermodynamics because it allows us to study the behavior of gases under constant temperature conditions. This process is often used in industrial applications, such as refrigeration, where maintaining a constant temperature is crucial for the proper functioning of the system.

5. What are some real-life examples of isothermal compression/expansion?

Some real-life examples of isothermal compression/expansion include the operation of a refrigerator or air conditioner, where a gas is compressed and expanded while maintaining a constant temperature. Another example is the use of compressed air in scuba diving tanks, where the temperature of the air is kept constant to prevent changes in pressure that could be dangerous for the diver.

Similar threads

  • Advanced Physics Homework Help
Replies
2
Views
7K
  • Advanced Physics Homework Help
Replies
4
Views
1K
  • Advanced Physics Homework Help
Replies
5
Views
1K
Replies
1
Views
654
Replies
2
Views
576
  • Advanced Physics Homework Help
Replies
6
Views
3K
  • Introductory Physics Homework Help
Replies
3
Views
955
  • Advanced Physics Homework Help
Replies
14
Views
8K
  • Introductory Physics Homework Help
Replies
4
Views
617
  • Introductory Physics Homework Help
Replies
2
Views
2K
Back
Top