One mole of an ideal gas is taken through an adiabatic process where the temperature rises from 27°C to 37°C.

Question:

One mole of an ideal gas is taken through an adiabatic process where the temperature rises from 27°C to 37°C. If the ideal gas is composed of polyatomic molecule that has 4 vibrational modes, which of the following is true? 

$\left[\mathrm{R}=8.314 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{k}^{-1}\right]$

  1. work done by the gas is close to 332 J 

  2. work done on the gas is close to 582 J

  3. work done by the gas is close to 582 J

  4. work done on the gas is close to 332 J 


Correct Option: , 4

Solution:

Since, each vibrational mode, corresponds to two degrees of freedom, hence, f = 3 (trans.) + 3(rot.) + 8 (vib.) = 14

$\& \quad \gamma=1+\frac{2}{f}$

$\gamma=1+\frac{2}{14}=\frac{8}{7}$

$\mathrm{W}=\frac{\mathrm{nR} \Delta \mathrm{T}}{\gamma-\mathrm{l}}=-582$

As $\mathrm{W}<0$. work is done on the gas. 

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