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saw5 [17]
3 years ago
11

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about 4.4x 10 m/s Calculate the

least possible uncertainty in a measurement of the speed of an electron in an atom of helium. Write your answer as a percentage of the average speed, and round it to 2 significant digits x 10
Chemistry
1 answer:
otez555 [7]3 years ago
3 0

The question is incomplete, here is the complete question:

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about 4.4\times 10^6m/s. Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of helium. Write your answer as a percentage of the average speed, and round it to 2 significant digits

<u>Answer:</u> The percentage of average speed is 41 %

<u>Explanation:</u>

We are given:

Radius of helium atom = 31 pm = 31\times 10^{-12}m    (Conversion factor:  1m=10^{12}pm )

So, diameter of helium atom = (2\times r)=(2\times 31\times 10^{-12})=64\times 10^{-12}m

The diameter of the atom will be equal to the uncertainty in position.

The equation representing Heisenberg's uncertainty principle follows:

\Delta x.\Delta p=\frac{h}{2\pi}

where,

\Delta x = uncertainty in position = d = 64\times 10^{-12}m

\Delta p = uncertainty in momentum  = m\Delta v

m = mass of electron = 9.1095\times 10^{-31}kg

h = Planck's constant = 6.627\times 10^{-34}kgm^2/s^2

Putting values in above equation, we get:

64\times 10^{-12}m\times 9.1095\times 10^{-31}kg\times \Delta v=\frac{6.627\times 10^{-34}kgm^2/s}{2\times 3.14}\\\\\Delta v=\frac{6.627\times 10^{-34}kgm^2/s^2}{2\times 3.14\times 64\times 10^{-12}m\times 9.1095\times 10^{-31}kg}=1.81\times 10^6m/s

To calculate the percentage of average speed, we use the equation:

\text{Percentage of the average speed}=\frac{\text{Uncertainty in velocity}}{\text{Average orbital speed}}\times 100

We are given:

Average orbital speed = 4.4\times 10^6m/s

Putting values in above equation, we get:

\text{Percentage of the average speed}=\frac{1.81\times 10^6m/s}{4.4\times 10^6m/s}\times 100\\\\\text{Percentage of the average speed}=41.\%

Hence, the percentage of average speed is 41 %

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