The atmosphere of the sun consists mostly of hydrogen atoms (not molecules) at a temperature of 6000 K. What are (a) the average translational kinetic energy per atom and (b) the rms speed of the atoms

Respuesta :

Explanation:

(a)  Formula for average translational kinetic energy of a particle is as follows.

                   U = [tex]\frac{3}{2}(\frac{RT}{N})[/tex]

where,   R = Reydberg's constant

              T = absolute temperature

              N = Avogadro's number

Therefore, we will calculate value of average translational kinetic energy as follows.

                 U = [tex]\frac{3}{2}(\frac{RT}{N})[/tex]

                    = [tex]\frac{3}{2}(\frac{8.314 J/mol K \times 6000 K}{6.023 \times 10^{23} mol^{-1}})[/tex]

                    = [tex]1.24 \times 10^{-19}[/tex] J

Therefore, value of average translational kinetic energy is [tex]1.24 \times 10^{-19}[/tex] J.

(b)   Formula for average kinetic energy is as follows.

             K.E = [tex]\frac{1}{2}(\frac{M}{N})v^{2}_{rms}[/tex]

Here,   M = molar mass = 1 kg/K mol

And, the average kinetic energy is equal to the average translational kinetic energy.

Hence,   K.E = U

     [tex]\frac{1}{2}(\frac{M}{N})v^{2}_{rms}[/tex] = [tex]\frac{3}{2}(\frac{RT}{N})[/tex]

            [tex]v^{2}_{rms} = \frac{3RT}{M}[/tex]

            [tex]v = \sqrt{\frac{3RT}{M}}[/tex]

therefore, we will calculate r.m.s speed of the given atom as follows.

              [tex]v = \sqrt{\frac{3RT}{M}}[/tex]

              [tex]v = \sqrt{\frac{3 \times 8.314 J/mol K \times 6000 K}{1 kg/K mol}}[/tex]

              = 386.84 m/s

Hence, value of r.m.s speed of the given atom is 386.84 m/s.

Following are the solution to the given points:

Given:

Temperature [tex]= 6000\ K[/tex]

To find:

kinetic energy =?

rms speed of the atoms=?

Solution:

For point a)

[tex]\to Avg \ KE =\frac{3}{2}\ KT \\\\[/tex]

[tex]\to KE_{avg} =1.5 \times 1.38 \times 10^{-23} \times 6000 \\\\[/tex]

                [tex]=1.5 \times 1.38 \times 10^{-23} \times 6000 \\\\=2.07 \times 10^{-23} \times 6000 \\\\=2.07 \times 10^{-23} \times 6000 \\\\=12.420 \times 10^{-20}\ J[/tex]

For point b)

[tex]\to[/tex] rms speed [tex]V_{rms}[/tex]:  

[tex]\to v_{rms}=\sqrt{\frac{3RT}{M}}[/tex]

             [tex]=\sqrt{\frac{3 \times 8314 \times 6000}{1}} \\\\=\sqrt{\frac{24942\times 6000}{1}} \\\\=\sqrt{149652000}\\\\=12233.233\\\\ = 12233\ \frac{m}{s}[/tex]

Therefore, the final answer is "[tex]12.420 \times 10^{-20} \ J\ \ and \ \ 12233 \ \frac{m}{s}[/tex]".

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