Chemical Thermodynamics Question 35

Question: The volume of a gas decreases from $ 500,cc $ to $ 300,cc $ when a sample of gas is compressed by an average pressure of 0.6 atm. During this process 10 J of heat is liberated. The change in internal energy is [Pb. PMT 2000]

Options:

A) - 2.16 J

B) 12.156 J

C) 2.16 J

D) 101.3 J

Show Answer

Answer:

Correct Answer: C

Solution:

Here: Change in Volume $ (V)=500-300=200cc=0.2,litre, $

Pressure $ (P)=0.6,atm $ and heat liberated (q) = 10J Work done $ (W)=P\Delta V=(0.2\times 0.6)=0.12,litre-atm $

But $ 1,litre-atm=101.3,J $ . hence $ W=0.12\times 101.3=12.156,J $ .

We also know that heat is liberated, therefore it would be negative. Thus change in $ \Delta E=q+W=-10+12.16=2.16,J $ .



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