L. an ideal gas consists of three dimensional polyatomi olecules. the temperature is such that only one vibrational mode is excited, if r denotes the gas consta

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mam, please give idea about no of rotational, translational, vibrational motion for each monoatomic, diatomic, triatomic and poly atomic molecule

i have not much knowlege about it

but i met several questions relating it

okay ,give me sometime, i'll provide u

yes mam

sir, thank u

i have another doubt relating to this question.

what's the doubt?

one minute please

if the molecule is polyatomic but not specifying vibrational mode then its cv=3R right???

CV=fR/2,where f is the degree of freedom,for a polyatomic gas molecule there are 3translational degree of freedom and 3 rotational degree of freedom.total 3+3=6.Hence using CV=fR/2=6*R/2=3R

but Cv=fR/2 can't be directly used when vibrational modes are there,if you are using this formula in vibrational mode case,then for one vibrational mode there will be two degrees of freedom

ok

f=3(translational)+3(rotational)+2(vibrational)=8.note-for one vibrational mode 2 degree of freedom will be there.Now using CV=fR/2=8R/2=4R

i have found many questions on this area

can i ask two more question??

ok

look at this question

i hope its clear to u, i mean clarity

D

yes sir

sir, please tell me the no of translational, rotational, vibrational motion for each monoatomic, diatomic, triatomic, polyatomic molecule

see attached

Note-Generally vibrational modes are not counted while calculating the degree of freedom unless it is mentioned in the question because vibrational modes are excited at very high temperatures. If your first question of polyatomic gass molecule it was mentioned that vibrational modes are excited.Hence that will be considered while calculating the degrees of freedom. And in your second question of O2 molecule it wasn't mentioned,hence only 5degrre of freedom are considered.

thank u so much sir

hope it will brush up your concept

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