Consider a gas of triatomic molecules. The molecules are assumed to be triangular and made of massless rigid rods whose vertices are occupied by atoms. The internal energy of a mole of the gas at temperature T is:
Consider a gas of triatomic molecules. The molecules are assumed to be triangular and made of massless rigid rods whose vertices are occupied by atoms. The internal energy of a mole of the gas at temperature T is:
Option 1 -
(5/2)RT
Option 2 -
(9/2)RT
Option 3 -
3RT
Option 4 -
(7/2)RT
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1 Answer
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Correct Option - 3
Detailed Solution:The internal energy of one mole of an ideal gas is given by U = (f/2)RT, where f is the number of degrees of freedom.
For a non-linear triatomic molecule (assumed to be a rigid rotator), there are:3 translational degrees of freedom.
3 rotational degrees of freedom.
Vibrational modes are generally not considered at temperature T unless specified.
Total degrees of freedom f = 3 + 3 = 6.
U = (6/2)RT = 3RT.
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