Explain the degree of freedom in thermodynamics
Answers
Answer:
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Explanation:
Statistical Thermodynamics and Rate Theories/Degrees of freedom. Molecular degrees of freedom refer to the number of ways a molecule in the gas phase may move, rotate, or vibrate in space. ... These molecular degrees of freedom essentially describe how a molecule is able to contain and distribute its energy.
degree of freedom is defined as the number of independent ways through which a system can exchange energy.
Degree of freedom are of three types
1) translational
2) rotational
3)vibrational
note :- vibrational DOF is not considered to be active at low temperatures.
1) for monoatomic gas example:- He
-> translational degree of freedom is = 3
(note:- translational motion means straight line motion)
becoz the monoatomic gas contains one atom that can move in the three axis x , y, z independently
-> rotational degree of freedom is zero becoz see rotation is always performed about an external axis
for example the Earth rotates around the sun and it spins about its own axis .
In case of monoatomic gas the atom can't perform rotation about an axis becoz if it performs then the rotation will depend on the other axis
if the atom rotates about the y axis then it's co-ordinates through which it will pass during the rotation will depend on the x- coordinate and z-coordinate
2) for diatomic gas example:- CO
-> translational degree of freedom is 3
-> rotational degree of freedom is 2
total degree of freedom is 5
3) triatomic gas linear gas example:- CO2
-> translational degree of freedom is 3
-> rotational degree of freedom is 2
4) triatomic non linear gas example:- SO2
-> translational degree of freedom is 3
-> rotational degree of freedom is 3
5) polyatomic gas example:- CH4
-> translational degree of freedom= 3
-> rotational degree of freedom is 3
now to calculate vibrational degree of freedom the formula used is
vibrational degree of freedom = 3N - (translational degree of freedom + rotational degree of freedom)
N = atomicity i.e. no of atoms present in the gas