Derive the equation of $v_{rms}$ in terms of molar mass.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) The average kinetic energy of one molecule of an ideal gas is given by:
$<\frac{1}{2} m v^{2}> = \frac{3}{2} k_{B} T$
Here,$m$ is the mass of one molecule,$v$ is the velocity,$k_{B}$ is the Boltzmann constant,and $T$ is the absolute temperature.
We know that the Boltzmann constant $k_{B} = \frac{R}{N_{A}}$,where $R$ is the universal gas constant and $N_{A}$ is the Avogadro number.
Substituting $k_{B}$ into the equation:
$<\frac{1}{2} m v^{2}> = \frac{3}{2} (\frac{R}{N_{A}}) T$
Multiplying both sides by $2$:
$m = \frac{3 R T}{N_{A}}$
Since the molar mass $M_{0} = m \times N_{A}$,we can write $m = \frac{M_{0}}{N_{A}}$. Substituting this:
$(\frac{M_{0}}{N_{A}}) = \frac{3 R T}{N_{A}}$
Canceling $N_{A}$ from both sides:
$M_{0} = 3 R T$
$ = \frac{3 R T}{M_{0}}$
By definition,the root mean square velocity $v_{rms} = \sqrt{}$.
Therefore,$v_{rms} = \sqrt{\frac{3 R T}{M_{0}}}$.

Explore More

Similar Questions

If a gas is compressed isothermally,then the r.m.s. velocity of its molecules

The $rms$ speed of oxygen at $27^{\circ}C$ will be .... $ms^{-1}$.

The $r.m.s.$ speed of the molecules of a gas in a vessel is $400 \; m/s$. If half of the gas leaks out,at constant temperature,the $r.m.s.$ speed of the remaining molecules will be ..... $m/s$.

At what temperature $(^oC)$ will the $rms$ speed of hydrogen be double its value at $S.T.P.$? The pressure remains constant.

Difficult
View Solution

The gas having an average speed four times that of $SO_2$ (molecular mass $64$) is

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo