Electron Emission Sig Figs

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Jennifer_Lam_1A
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Joined: Wed Sep 21, 2016 2:56 pm

Electron Emission Sig Figs

Postby Jennifer_Lam_1A » Mon Oct 10, 2016 7:41 pm

Hi everyone! I had a question regarding the sigfigs about electron emission. When using Rydberg's equation, certain questions only give out the energy level (i.e. n=3). When calculating the answer, do we use the sigfigs given in the Rydberg constant or from the energy level?
Here is Rydberg's equation for reference: E= -hR/(n^2)

Chem_Mod
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Re: Electron Emission Sig Figs

Postby Chem_Mod » Mon Oct 10, 2016 8:51 pm

The n^2 term in the equation is the result of derivation, and it is absolute. This means that the n values do not have error associated with the values, and thus no significant figures. For example, when finding the mass of 4 bananas, you would multiply the 4 with the mass of a banana. That 4 does not have to be considered in the significant figures of the final answer. Now that the n^2 term is explained, what is left to be considered in the significant figures of the equation?

JennaMinami1I
Posts: 18
Joined: Wed Sep 21, 2016 2:56 pm

Re: Electron Emission Sig Figs

Postby JennaMinami1I » Tue Oct 11, 2016 3:03 pm

Hello!

I had a similar questions and asked my TA... I had put 4 sig figs in my answer, which I derived from Planck's Constant (6.626*10^-34), and he said that would be the best, since the energy levels (n=#) are constants.

Use the number of sigfigs in Planck's Constant, which is 4!

(I hope this is actually correct!)


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