- #1
ricard.py
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Hello,
I have been self-learning Thermodynamics and I am having a bit of trouble with calculating the work in different circumstances.
Along the lectures we have come up with three different equations for work
1) W = pΔV
2) W = nRTln(V2/V1)
3) W = CvΔT
So my questions are:
1) which ones must be used in which type of thermodynamic process? For instance, the third is used in adiabatic processes, but the second
2) If using the second formula in a reaction that changes the temperature along it, we have to take as T the initial temperature, the last temperature, the difference..?
2) Accoding to the first equation, if V is constant, then W=0. However, according to the last formula the work only depends on T and we can get work done without modifying the volume. Why this is not contradictory?
Thanks!
I have been self-learning Thermodynamics and I am having a bit of trouble with calculating the work in different circumstances.
Along the lectures we have come up with three different equations for work
1) W = pΔV
2) W = nRTln(V2/V1)
3) W = CvΔT
So my questions are:
1) which ones must be used in which type of thermodynamic process? For instance, the third is used in adiabatic processes, but the second
2) If using the second formula in a reaction that changes the temperature along it, we have to take as T the initial temperature, the last temperature, the difference..?
2) Accoding to the first equation, if V is constant, then W=0. However, according to the last formula the work only depends on T and we can get work done without modifying the volume. Why this is not contradictory?
Thanks!