AZING GAS LAWS: Internal Energy Change in Adiabatic Processes

[Bradracer18]

I need a little starter on this one...can't figure out how to do it(or even start it)...I'll work it, if I can get some help along the way...


Two moles of an ideal gas at 20 deg C undergo a free adiabatic expansion from 2.0 liters to 66 liters. Then the gas is adiabatically compressed such that the pressure is inversely proportional to the square of the volume: P=P(not)(V(not)/V)^2. What is the total internal energy change after both processes if the last compression reduces the volume by a factor of 4.


The problem is kinda hard to understand in itself for me...so any help would be greatly appreciated.

Thanks,
Brad

 

[Bradracer18]

anyone else understand this problem enough to help me along??

 

[Andrew Mason]

Two moles of an ideal gas at 20 deg C undergo a free adiabatic expansion from 2.0 liters to 66 liters. Then the gas is adiabatically compressed such that the pressure is inversely proportional to the square of the volume: P=P(not)(V(not)/V)^2. What is the total internal energy change after both processes if the last compression reduces the volume by a factor of 4.

What is the relationship between Pressure and Volume in an adiabatic compression or expansion? (Hint: it depends on C_P/C_V for the gas. How do you determine $\gamma$ for this particular gas?)

What is the expression for the internal energy of a gas? (what property does it depend on?) Can you determine that property from the information provided?

AM