1for the whole gas it is 19/14
Calculate the value of γ =Cp/Cv for a gaseous mixture consisting of v1=2.0 moles of oxygen and v2=3.0 moles of carbon dioxide. The gases are assumed to be ideal!
(This question was given by ashish.. It was attempted by a couple of users.. But I felt that the attempts were not correct enuf!)
(Sorry for the delay in the question of the days over the last few days.. there will be delays for the next few as well. I have been busy with other stuff on the site which might not be visible immediately but u guys will see the change.. albeit slowly)
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17 Answers
62that is my point ..
1.29 seems closer to 1+2/7 than 1+2/6!
Irodov also seems to concur to this.. and has solved it using 1+2/7!
But yeah.. as u can see it is still open to a lot of discussion!
1for CO2:
Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 °C (77 °F)) : 1.293759
source:http://encyclopedia.airliquide.com/Encyclopedia.asp?GasID=26
62Heat capacity ratio γ = cp/cv
1.37 at –75°C
1.310 at 0°C
1.304 at 15°C
1.281 at 100°C
1.235 at 400°C
1.195 at 1000°C
1.171 at 2000°C
Source: Wikipedia
Now for our problem, we wud be operating at what (25 degrees!)
So gamma is very controversial. It falls in between both the values (1.33=1+2/6 and 1.285 =1+2/7)
The other thing..
The answer in Irodov (I am sure it cant be wrong!) is 1.33
So I am sure we still have something to discuss here? :)
I know you guys have given a decent answer.. But i guess I am not convinced enuf. (The more important thing is that you should be convinced yourself!)
9for
co2
there are 6 degrees of freedom
3 translatory
2 rotatory
1 harmonic motion abot C
i hope this satisfies
1arey!! wat was the prob wid my method dat i posted for ashish's question??
it was this only..
total Cp/ total Cv... !!
1i took it to be polyatomic but yes as it is linear and if it always remains linear during brownian motion ,
then maybe it will not be just 4/3
i hv my doubts
62Hehe.. did I go wrong in the question of the day :D (never mind)
I had a completely different expression in mind.. I felt it wud never equate to this one :D
Neways.. how did u get the gamma for CO2
there are a few things in that one..
1) Do u consider it's degrees of freedom?
taking it as a bimolecular or trimolecular atom.. (remember that its shape is linear!) (and not bent as SO2 or some other bimolecular gasses/ atoms!)
1357u are right Rohan
the method will work
Can you find the numerical value of γ?
1yes it does..
as Cpeq=n1Cp1+n2Cp2/n1+n2
and Cveq=n2Cv2+n1Cv1/n1+n2
here Cp1=R+Cv1
and Cp2=R+Cv2
placing them we get Cpeq=Cveq +R
62Hmm.. weel celestine.. the expression is not correct...
Ur method will not work here!
ur method should give
Cp-Cv=R (for the total gas.. ) does it?
62Yeah.. i think it is a good concept to knwo the degrees of freedom of CO2
and Then the concpet to be used in solving this problem above..
9gamma co2 is 4/3
gamma eff = tot cp/tot cv = n1Cp1 + n2Cp2 / n1Cv1 + n2Cv2
62I dont want answers I want the method..
1) What is the gamma that you take of CO2 and why
2) What was the method employed?