Change in entropy for adiabatic compression

GAMGIn summary, the problem involves a sample of nitrogen gas that is adiabatically compressed to half its original volume. The question asks for the change in entropy of the gas. To solve this, the adiabatic condition, which relates pressure and volume in an adiabatic change, should be used. The condition takes into account the value of \gamma, which is 1.4 for nitrogen gas. This can then be used in the equations PV=nRT and S2-S1=CvIn(P2/P1)+CpIn(V2/V1).
  • #1
Bugsy23
25
0

Homework Statement



A sample of 8.02*10^-1 moles of nitrogen gas ([tex]\gamma[/tex]=1.4) occupies a volume of 2*10^-2m^3 at pressure 1*10^5pa and temperature 300K. The gas is adiabatically compressed to half its original volume. What is the change in entropy of the gas?


Homework Equations



S2-S1=CvIn(P2/P1)+CpIn(V2/V1)

PV=nRT

The Attempt at a Solution



I have already worked out the values for Cv and Cp and the change in volume of the gas, but I don't know how to find the change in pressure. Since nitrogen behaves as an ideal gas, it should be possible to find it using PV=nRT, but that also requires knowing the change in temperature. Is there a different way of working out the change in pressure?
 
Physics news on Phys.org
  • #2
You have to use the adiabatic condition. This condition shows the relationship between P and V in an adiabatic change. Hint: it uses [itex]\gamma[/itex]

AM
 

FAQ: Change in entropy for adiabatic compression

1. What is adiabatic compression?

Adiabatic compression refers to the process of compressing a gas or substance without any heat transfer occurring. This means that the temperature of the substance remains constant during the compression process.

2. How does adiabatic compression impact entropy?

During adiabatic compression, the entropy of a substance decreases. This is because the compression process reduces the disorder of the substance, resulting in a decrease in entropy.

3. What factors affect the change in entropy for adiabatic compression?

The change in entropy for adiabatic compression is affected by the initial and final temperatures of the substance, as well as the pressure and volume of the substance before and after compression.

4. Why is adiabatic compression important in thermodynamics?

Adiabatic compression is important in thermodynamics because it is a process that happens in many real-world scenarios, such as in the compression of gases in engines and refrigerators. It also helps us understand the relationship between pressure, volume, and temperature in thermodynamic systems.

5. How is the change in entropy for adiabatic compression calculated?

The change in entropy for adiabatic compression can be calculated using the formula ΔS = nCln(Tfinal/Tinitial), where n is the number of moles of the substance and C is the molar heat capacity at constant volume.

Similar threads

Adiabatic condition and equation of state
Replies
7
Views
3K
Adiabatic Expansion of Pressurized Air in a Piston-Cylinder Setup
Replies
8
Views
1K
Isothermic and adiabatic compression
Replies
17
Views
2K
Finding the pressure of a gas in three identical balloons
Replies
12
Views
1K
Gas temperature in a constant volume
Replies
8
Views
1K
Work done in adiabatic process vs work done in isothermal
Replies
2
Views
2K
What is the volume of the gas after adiabatic compression
Replies
2
Views
1K
Change in entropy of an ideal gas during thermodynamic cycle
Replies
1
Views
2K
Ideal Gas Law -- Isobaric Epansion followed by....
Replies
9
Views
2K
Entropy Change - Irreversible Isothermal Compression
Replies
5
Views
3K

Hot Threads

Recent Insights

Back
Top