Thermo Question - Stuck bigtime~

  • Thread starter swandive76
  • Start date
  • #1
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
 

Answers and Replies

  • #2
berkeman
Mentor
59,083
9,189
What are the relevant equations? Can you show us how you think you should approach this problem?
 
  • #3
261
2
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
Andrew Mason
Science Advisor
Homework Helper
7,657
384
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
 

Related Threads on Thermo Question - Stuck bigtime~

  • Last Post
Replies
1
Views
949
  • Last Post
Replies
2
Views
920
  • Last Post
Replies
5
Views
2K
Replies
6
Views
1K
Replies
6
Views
4K
  • Last Post
Replies
1
Views
958
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
4
Views
2K
  • Last Post
Replies
6
Views
1K
Top