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

At a temperature of $27^{\circ}C$ and a pressure of $1.0 \times 10^5 \, N/m^2$,the $rms$ speed of a gas is $200 \, m/s$. What is the $rms$ speed at a temperature of $127^{\circ}C$ and a pressure of $0.5 \times 10^5 \, N/m^2$?

At what $^\circ C$ temperature will the molecules of nitrogen have the same $rms$ velocity as the molecules of oxygen at $127^\circ C$?

Difficult
View Solution

What is the order of the speed of gas molecules?

What is $rms$ value? What is $v_{rms}$? Derive the equation of $v_{rms}$ in terms of pressure.

The $r.m.s.$ velocity will be greater for

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