A gas of helium atoms (each of mass 6.65 × 10-27 kg) are at room temperature of 20.0°C. What is the de Broglie wavelength of the helium atoms that are moving at the root-mean-square speed? (h = 6.626 × 10-34 J · s, the Boltzmann constant is 1.38 × 10-23 J/K)

Respuesta :

Answer:

The de Broglie wavelength of the helium atoms is [tex]7.373\times10^{-11}\ m[/tex].

Explanation:

Given that,

Mass [tex]M=6.65\times10^{-27}\ kg[/tex]

Temperature = 20.0°C

We need to calculate the root-mean square speed

Using formula of root mean square speed

[tex]v_{rms}=\sqrt{\dfrac{3kTN_{A}}{M}}[/tex]

Where, N = Avogadro number

M = Molar mass

T = Temperature

k = Boltzmann constant

Put the value into the formula

[tex]v_{rms}=\sqrt{\dfrac{3\times1.38\times10^{-23}\times293\times6.022\times10^{23}}{4\times10^{-3}}}[/tex]

[tex]v_{rms}=1351.37\ m/s[/tex]

We need to calculate the de Broglie wavelength

Using formula of de Broglie wavelength

[tex]P=\dfrac{h}{\lambda}[/tex]

[tex]mv=\dfrac{h}{\lambda}[/tex]

[tex]\lambda=\dfrac{6.626\times10^{-34}}{6.65\times10^{-27}\times1351.37}[/tex]

[tex]\lambda=7.373\times10^{-11}\ m[/tex]

Hence, The de Broglie wavelength of the helium atoms is [tex]7.373\times10^{-11}\ m[/tex].

The de Broglie wavelength of the helium atoms is mathematically given as

7.373*10^{-11} m.

What is the de Broglie wavelength of the helium atoms that are moving at the root-mean-square speed?

Question Parameter(s):

A gas of helium atoms (each of mass 6.65 × 10-27 kg) is at room temperature of 20.0°C.

Generally, the equation for the Speed   is mathematically given as

[tex]v_r =\sqrt{\frac{3kTN_{A}}{M}}[/tex]

Therefore

[tex]v_{rms}=\sqrt{\frac{3*1.38*10^{-23}*293*6.022*10^{23}}{4*10^{-3}}}[/tex]

v_r=1351.37 m/s

In conclusion, de Broglie wavelength is

[tex]p=h/\lambda[/tex]

Therefore

[tex]\lambda=\frac{6.626*10^{-34}}{6.65*10^{-27}*1351.37}[/tex]

7.373*10^{-11} m.

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