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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:08 PM
Original message
Chemistry repeat performance?
Last time I had a really hard chemistry problem. 4 weeks ago, DU bailed my ass out.
Its been rather painful as I've been working on this for about 8 hours. I got all the other ones in this set except this one. :eyes:
A repeat performance please?



λ for one line of the hydrogen spectrum is .4118 x 10-4 cm. Use this value in the Rydberg equation to calculate the RH value using n1 = 2, and n2 = 3.

So heres what I did.
I took .4118X10-4 cm and made it into m.

So λ=.4118 X 10-6 m

then

1/λ= R(1/n1-1/n2)

1/.4118 X 10-6 = R(5/36)

1/R=.00000057/1
.00000057R=1
R=1754385.965
R=1.754X10^-6

This is apparently wrong. Any hints, tips, solutions, ect. would be greatly appreciated. :)
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 10:21 PM
Response to Original message
1. Is it
Edited on Sun Oct-08-06 10:21 PM by sir_captain
1.748*10^7 m^-1?
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:23 PM
Response to Reply #1
2. no
:(
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 10:25 PM
Response to Reply #2
3. hmm
well, for one thing, you forgot to square your n's in the equation you wrote

i will have to ponder this slightly longer--hope i can help
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:29 PM
Response to Reply #3
4. i just couldnt find the easy way to make the squares and didnt bother
if i wrote out the entire thing i did, it would have been
1/n1 - 1/n2
1/22 - 1/32
1/4- 1/9
9/36-4/36
5/36
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 10:32 PM
Response to Reply #4
5. do you have the correct answer?
this seems to be a pretty straight-forward balmer series problem. i'm a little puzzled about the wavelength you have to start with, though.
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:46 PM
Response to Reply #5
7. I get chemistry hw and prelabs on this stupid thing called CAPA
basically, if its not in a form its happy with, it sends hate through the internet tubes.

2. <1pt>
λ for one line of the hydrogen spectrum is .4118 x 10-4 cm. Use this value in the Rydberg equation to calculate the RH value using n1 = 2, and n2 = 3.

Answer: <____________>
Last Answer: 1.754e7
Incorrect, tries 28/99.

1.748e7 didnt work either :(
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 10:53 PM
Response to Reply #7
9. That's weird
I'm reasonably certain that is the correct answer given the information you have been given.

You could try 1.75e7 and see if it only wants one decimal point or something.
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:57 PM
Response to Reply #9
10. I did try that,
λ for one line of the hydrogen spectrum is .4118 x 10-4 cm. Use this value in the Rydberg equation to calculate the RH value using n1 = 2, and n2 = 3.

Answer:<>
Last Answer: 1.75e7
Please adjust significant figures, tries 32/99.

I'm about to fix my computer with a hammer.
Everyone is saying that is my answer, but CAPA says 'NO! lolz.' :(
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 11:00 PM
Response to Reply #10
11. The whole question is dumb
why would they want you to calculate a constant? This equation is normally used to calculate a wavelength, not the other way around. And 411nm is an odd wavelength for hydrogen.
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 11:08 PM
Response to Reply #11
12. I agree that it is dumb
However, despite the dumbness, I still need to figure it out.
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Ptah Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 10:39 PM
Response to Original message
6. It this the misstep?
R=1754385.965
R=1.754X10^-6

Shouldn't that be R=1.754X10^6

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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 10:46 PM
Response to Reply #6
8. yeah it should
but that isnt it either. :(
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 11:24 PM
Response to Original message
13. I posted this on Freeperville but I got the answer
"Type 'God did it' "

Not really. Just bumping the thread a little with a joke.
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Sun Oct-08-06 11:29 PM
Response to Reply #13
14. Sorry I can't be more help
do you know anyone who has gotten it right?
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akushuki Donating Member (277 posts) Send PM | Profile | Ignore Sun Oct-08-06 11:31 PM
Response to Reply #14
15. no
Every other person in chemistry 111 on my floor has lab on Thursday and dont do them until tuesday/wednesday. I have mine on Monday, which is in about 11 1/2 hours from now. :(

I started at 3 yesterday(sunday)
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sir_captain Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Oct-09-06 12:03 AM
Response to Reply #15
16. That sucks
if it makes you feel any better, I've been memorizing the anatomy of the back and upper limb pretty much non-stop since friday night.

How much is this one question worth, relatively?
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