Learning undergraduate engineering thermodynamics might be less painful with a blog. I hope that students, faculty and interested observers will share their thoughts on the laws of thermodynamics, phase and chemical equilibrium and many related topics.
Please post any questions or discussion related to this problem as comments on this message. Feel free to answer other students' questions. I will check the blog M-F and once on the weekend. Dr. B
7 comments:
Anonymous
said...
do we not need to know the molecular weight of the air to find V wiggle?
I'm confused about which R value units to use in the ideal gas EOS. I'm was planning on using the AE units of psia, ft^3, and degrees F but don't see an R that matches those units. Any shoves in the right direction would be appreciated.
clueless: In the unit conversion table in the back of the Thermo CD workbook, you will find R in many unit systems. The best choice for this problem is probably R = 10.73 psia-ft^3/lbmole-degR.
Converting everything to SI is time consuming and gives you too many chances to make a mistake.
7 comments:
do we not need to know the molecular weight of the air to find V wiggle?
jtl610:
Yes, you need to know the MW of air. It is 29 g/mole or lbm/lbmole.
I think this is in an example in Thermo-CD, but it may not be in the book.
I'm confused about which R value units to use in the ideal gas EOS. I'm was planning on using the AE units of psia, ft^3, and degrees F but don't see an R that matches those units. Any shoves in the right direction would be appreciated.
I just converted everything to atm, liters, and Kelvin so I could use .08206 L-atm/K-mol. Hope that's good enough...
clueless:
In the unit conversion table in the back of the Thermo CD workbook, you will find R in many unit systems. The best choice for this problem is probably R = 10.73 psia-ft^3/lbmole-degR.
Converting everything to SI is time consuming and gives you too many chances to make a mistake.
how does one convert a gmole to a lbmole?
questioning:
I avoid switching systems of units in general.
But because there are 453.593 g/lbm, there are also 453.593 lbm/lbmole.
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