Thermodynamics and Thermochemistry 1 Question 27

30. A monoatomic ideal gas undergoes a process in which the ratio of p to V at any instant is constant and equals to 1 . What is the molar heat capacity of the gas?

(2006, 3M)

(a) 4R2

(b) 3R2

(c) 5R2

(d) 0

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Solution:

  1. Given, pV=1p=V

Also from first law : dq=CVdT+pdV

For one mole of an ideal gas : pV=RT

pdV+Vdp=RdT  From (i) pdV=Vdp

Substituting in Eq. (ii) gives

2pdV=RdTpdV=R2dT dq=CVdT+R2dT dqdT=CV+R2=32R+R2=2R