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Topic: Help with hydrogen spectral lines -->hz--->energy  (Read 3564 times)

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Offline loldog1

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Help with hydrogen spectral lines -->hz--->energy
« on: October 06, 2011, 09:20:08 PM »
For hydrogen's red spectral line, I got 660nm, which I plugged into the equation 3E8=lambdaV to the the frequency, V.

3E8=660V-----> V= 4.55E5 hz after sig figs

Then, I plugged the frequency into the equation E=hv

E=6.626E-34 x 4.55E5hz------>E= 4.62E-28 after sig figs

Now here's where I'm stuck. I have to plug in 4.62E-28 into Bohr's equation: E=-2.178x10-18 J[(1/2^2)-(1/n^2)] to find the energy level transition, n. I know for a fact some value is wrong, but I don't know what. This website ( http://faculty.kfupm.edu.sa/CHEM/mnahid/Quizzes/Quiz7-Chap7-sol.pdf ) is saying that my value for E should be -4.088x10-19 and mine is no where close. What did I do wrong?
« Last Edit: October 06, 2011, 09:32:43 PM by loldog1 »

Offline Borek

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Re: Help with hydrogen spectral lines -->hz--->energy
« Reply #1 on: October 07, 2011, 02:46:52 AM »
For hydrogen's red spectral line, I got 660nm, which I plugged into the equation 3E8=lambdaV to the the frequency, V.

3E8=660V-----> V= 4.55E5 hz after sig figs

Watch your units.
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Offline loldog1

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Re: Help with hydrogen spectral lines -->hz--->energy
« Reply #2 on: October 08, 2011, 12:55:09 AM »
What is the correct unit my answers needs to be in?

Offline Borek

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Re: Help with hydrogen spectral lines -->hz--->energy
« Reply #3 on: October 08, 2011, 04:20:50 AM »
Hz is a correct unit, but your answer is not in Hz. Don't ignore units during calculations, and it will become obvious where the problem is.
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Offline loldog1

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Re: Help with hydrogen spectral lines -->hz--->energy
« Reply #4 on: October 08, 2011, 01:18:09 PM »
Ok, thanks for your help.

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