How Do You Calculate Properties of a Gas After Adiabatic Compression?

In summary, the conversation is about a question regarding the calculation of values for gamma, Cv, R, and molecular weight of a perfect gas that is compressed adiabatically from 100 kPa and 17C to 500 kPa and 77C. The work done during the compression is given as 45 kJ/kg. The person asking for help is advised to derive the relevant equations and to use the ideal gas law to determine unknown initial quantities. It is also suggested to consider the relationship between P and V in an adiabatic (reversible) change, which involves the use of gamma.
  • #1
swandive76
1
0
Hoping someone can help me here quickly. Trying to get this one question.

a perfect gas is compressed adiabatically from 100 kPa and 17C to a final pressure of 500 kPa and final temp of 77C. The work done during the compression is 45 kJ/kg. Calculate the values of gamma, Cv, R and the molecular weight of the gas.


Please let me know anything you can

Thanks in advance!

Swandive
 
Physics news on Phys.org
  • #2
What are the relevant equations? Can you show us how you think you should approach this problem?
 
  • #3
Have you ever derived the expression for adiabatic expansions yourself?

Working from the first law of thermodynamics and an equation of state (the ideal gas law), you should be able to come up with the expressions for work done by a gas in an adiabatic expansion, in addition to expressions for other quantities.

This problem is more of a calculator exercise. I highly recommend that you take the time to derive everything -- suffering through it once will make everything clear in the end. Go over isothermal, isobaric, isochoric, and adiabatic expansions.

You will also find that you will often have to use the ideal gas law to determine unknown initial quantities.
 
  • #4
swandive76 said:
Hoping someone can help me here quickly. Trying to get this one question.

a perfect gas is compressed adiabatically from 100 kPa and 17C to a final pressure of 500 kPa and final temp of 77C. The work done during the compression is 45 kJ/kg. Calculate the values of gamma, Cv, R and the molecular weight of the gas.
Assume this is a reversible adiabatic compression. What is the relationship between P and V in an adiabatic (reversible) change? (hint: it involves [itex]\gamma[/itex])

AM
 

1. What is thermodynamics?

Thermodynamics is a branch of physics that deals with the relationships between heat, energy, and work. It studies how energy is transferred and transformed in various systems, and how this affects the behavior of matter.

2. How does thermodynamics relate to everyday life?

Thermodynamics is present in many aspects of everyday life. For example, it explains how engines work, how food is digested in our bodies, and how refrigerators keep our food cold. It also plays a role in understanding weather patterns and the functioning of the Earth's climate.

3. What are the laws of thermodynamics?

The laws of thermodynamics are fundamental principles that govern the behavior of energy in a closed system. The first law states that energy cannot be created or destroyed, only transferred or transformed. The second law states that in any energy transfer or transformation, some energy will be lost as heat. The third law states that the entropy of a perfect crystal at absolute zero temperature is zero.

4. Why is thermodynamics important in science?

Thermodynamics is important in science because it helps us understand and predict the behavior of matter and energy. It is the basis for many fields of study, including chemistry, engineering, and meteorology. It also has practical applications in technology and industry, such as in the design of efficient engines and power plants.

5. What are some common applications of thermodynamics?

Some common applications of thermodynamics include refrigeration and air conditioning systems, power plants, engines, and chemical reactions. Thermodynamics is also used in the study of phase transitions, such as the melting and boiling of substances, and in the design of materials with specific thermal properties.

Similar threads

I Gas compression - does it double the energy?
    • Thermodynamics
Replies
6
Views
1K
B Energy seems to disappear when gas is compressed?
    • Thermodynamics
Replies
3
Views
1K
Adiabatic Expansion of Pressurized Air in a Piston-Cylinder Setup
    • Introductory Physics Homework Help
Replies
8
Views
745
How Do You Calculate Work When Compressing Gas?
    • Introductory Physics Homework Help
Replies
1
Views
1K
Temperature in the regulator valve of a cylinder
    • Advanced Physics Homework Help
Replies
1
Views
1K
Thermodynamics: Compression of an Adiabatic Gas
    • Biology and Chemistry Homework Help
Replies
2
Views
1K
I How Do You Calculate Initial Pressure and Final Volume in Adiabatic Expansion?
    • Classical Physics
Replies
7
Views
1K
Work done by gas and balloon?
    • Introductory Physics Homework Help
Replies
11
Views
3K
Adiabatic compressed air and energy calculations
    • Introductory Physics Homework Help
2
Replies
60
Views
5K
Can Adiabatic Processes Be Irreversible?
    • Introductory Physics Homework Help
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top