Choose the correct option for free expansion of an ideal gas under adiabatic condition from the following :
- q = 0, T = 0, w = 0
- q = 0, T 0, w = 0
- q 0, T = 0, w = 0
- q = 0, T < 0, w 0
Answer
(1) q = 0, T = 0, w = 0
Solution
Free expansion ⇒ expansion into vacuum ( pext = 0)
⇒ w = -pext V = 0
Adiabatic ⇒ q = 0
⇒ U = q + w = 0
∵ U of an ideal gas depends only on T ⇒ T = 0
Answer: (1)