1.

Calculate the average kinetic energy for one molecule of gas at constant volume.

Answer»

Pressure exerted by one mole of gas,

\(P=\frac{1}{3}ρv^2_{rms}\) 

\(=\frac{1}{3}\frac{M}{V}v^2_{rms}\) 

or, \(PV=\frac{1}{3}Mv^2_{rms}\) 

But  PV = RT

\(\frac{1}{3}Mv^2_{rms}\) = RT

\(Mv^2_{rms}\) = 3RT

Now, average KE

\(\frac{1}{3}Mv^2_{rms}\) = \(\frac{3}{2}\)RT

\(\frac{1}{2}(Nm)v^2\) = \(\frac{3}{2}\)RT (∵ M = Nm)

(KE)Avg for one mole

\(\frac{1}{3}Mv^2_{rms}\) = \(\frac{3}{2}\frac{R}{N}T\)\(\frac{3}{2}\)kBT

∴ Total random K.E. for one mole =\(\frac{3}{2}\)RT

and average K.E. per molecule = \(\frac{3}{2}\)kBT



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