# Thermodynamics Question Calculating change in temperature

1. Feb 3, 2015

### Gaith

1. The problem statement, all variables and given/known data
50 moles of an ideal gas for which Cp= 5/2R and Cv=3/2R initially has a pressure of 1x10^5 Pa, and a volume of 1.0m^3. It undergoes a process where the pressure and volume both double while they stay proporitional to each other: P=constV. What is the change in temperature for this process?

2. Relevant equations
ΔU= Q-W
PV=nRΔT
ΔU= nCv(ΔT)

3. The attempt at a solution
So I started by trying to use PV=nRΔT and calculating T, however I wasnt successful. The answer in my book is in Kelvins, so I tried converting the temperature that I calculated to Kelvins, however it was still wrong.

I'm thinking that I might need to take the integral: ∫ PVdv but im not sure if thats correct either.

Last edited: Feb 3, 2015
2. Feb 3, 2015

### TSny

Hello.
The above equation is not correct. The ideal gas law is PV = nRT, not PV = nRΔT.

From PV = nRT can you calculate the initial temperature? How about the final temperature?

3. Feb 3, 2015

### Staff: Mentor

From the ideal gas law, what is the initial temperature? From the ideal gas law, what is the final temperature?

Chet