# Need help with this heat capacity/ideal gas problem.

blehxpo
For many gases at low densities and pressures (where ideal gas behavior is obtained), Cv/R = A+BT+CT^2 where A, B, C, are all constants, with appropriate temperature units so that the RHS (right hand side) of this equation is dimensionless.

a> How can a gas be both ideal and follow the equation above, at the same time.

b> Such a gas initially at T1 expands slowly in an insulated piston to double its original volume you would like to find the final temperature T2. A friend suggest you may use the follow equation that we derived in class:

(T2/T1) = (V1/V2)^(R/Cv) = (1/2)^(R/Cv)

where Cv is evaluated at T1. What is wrong with your friend's statement? Find the correct equation that should be solved (implicitly) to find T2.

Attempt:
a. I said it has to be at constant V and high temperature. Not what it was asking
b. It said it was an insulated piston? Doesnt that mean that T1=T2?? But I have really no idea how to do it. :/