## Heinsberg Uncertainty Equation Post-Module Question #18

$\Delta p \Delta x\geq \frac{h}{4\pi }$

305086803
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Joined: Wed Sep 18, 2019 12:16 am

### Heinsberg Uncertainty Equation Post-Module Question #18

Hi everybody,

Here is the question as follows: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle.

So what I have done is find delta V after converting 0.05 nm to m and multiplying it by 0.01, and I got 5 x 10^-13 m, and then I multiplied that by the mass of a hydrogen atom in grams. I then plugged that into the equation to find delta p, but none of my answers were correct. Could someone explain to me where I went wrong, preferably step by step!

Thanks

Alex Chen 2L
Posts: 86
Joined: Wed Sep 18, 2019 12:21 am

### Re: Heinsberg Uncertainty Equation Post-Module Question #18

I believe you have to use the mass of an electron, not the mass of an hydrogen atom, because you're calculating the uncertainty in the speed of the electron itself. Also, the value for positional uncertainty that you found should be multiplied by two since you have to add the possibilities that the electron is 1% farther or that the electron is 1% closer to the nucleus than the radius length.

MaggieHan1L
Posts: 100
Joined: Thu Jul 11, 2019 12:17 am

### Re: Heinsberg Uncertainty Equation Post-Module Question #18

The uncertainty of the electron would be diameter and you used radius.

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