Thermodynamics Question 330
Question: The degrees of freedom per molecule of an ideal gas is 5. Work done by the gas is 100 J when it expands isobarically. The heat absorbed by the gas will be
Options:
A) 250 J
B) 150 J
C) 350 J
D) 200 J
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Degrees of freedom is 5
Hence $ C _{V}=\frac{5}{2}RT $ and $ C _{P}=\frac{7}{2}RT $
$ \frac{dQ}{dU}=\frac{nC _{P}dT}{nC _{V}dT}=\frac{C _{P}}{C _{V}} $
or $ \frac{dQ}{dQ-dW}=\frac{7}{5} $
$ \therefore $ $ dQ=3.5dW=3.5(100) $
$ =350J $
