Equating two formulas for root-mean-square velocity

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SUMMARY

The discussion confirms that all formulas related to root-mean-square velocity (vrms) are correct when considering molecular mass as the mass of a single molecule. The relationship established is vrms > average velocity > most probable velocity, affirming the hierarchy of these velocity measures. Participants agree on the accuracy of the formulas presented, ensuring clarity in their application.

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JC2000
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Homework Statement
Compare ##v_{rms}##, ##v_{most probable}## and ##v_{average}## (arrange them in increasing/decreasing order).
Relevant Equations
##v_{rms} = \sqrt {\frac{3RT}{M}}## where ##M## is molar mass of the gas. ... (1)
##v_{rms} = \sqrt {\frac{3k_{B}T}{m}}## where ##m## is the molecular mass of the gas. ...(2)
## N_A*k_B = n*R## where ##N_A## is Avogadro's number and ##n## is the number of moles of the gas.
## \frac{M}{N_A} = m## (?)
(a)
My question :
Are all the formulas correct?

If so I can write ##v_{rms}## in form (2) and compare that result with the other velocities to get the answer (rms > average > most probable)
 
Last edited:
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If by "molecular mass" you mean the mass of one molecule, then all of the above is correct.
 
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kuruman said:
If by "molecular mass" you mean the mass of one molecule, then all of the above is correct.

Yes, thanks for going through it all!
 

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