Thermodynamics Question 229

Question: A gas is compressed from a volume of 2m3 to a volume of 1m3 at a constant pressure of100N/m2 . Then it is heated at constant volume by supplying 150 J of energy. As a result, the internal energy of the gas:

Options:

A) increases by 250 J

B) decreases by 250 J

C) increases by 50 J

D) decreases by 50 J

Show Answer

Answer:

Correct Answer: A

Solution:

[a] As we know, ΔQ=ΔU+ΔW (1st law of thermodynamics) ΔQ=ΔU+PΔV

or 150=ΔU+100(12)=ΔU100

ΔU=150+100=250J

Thus the internal energy of the gas in- creases by 250 J



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