Chem Lab C

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Re: Chem Lab C

Post by starpug »

Paradox21 wrote:Does anyone know what kind of Chemistry book would talk about Beer's Law? I have looked in 2 college level general chemistry books and neither mentions it.
I saw it in a lab handout for a spectrophotometer lab in AP Chem class last year. I might be able to go dig it up.
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Re: Chem Lab C

Post by rocketman1555 »

I think you would be better looking in lab handouts and stuff for Beer's Law, though it should at least be mentioned in a Gen Chem book. http://www.chm.davidson.edu/vce/spectro ... rslaw.html: This might help.
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Re: Chem Lab C

Post by ribonucleicacid621 »

Beers' Law is pretty simple and there are some good web resources that explain the principal-rocketman's link is pretty good.
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Re: Chem Lab C

Post by EastStroudsburg13 »

Can someone explain to me exactly how, in a voltaic cell, how electrons flow between the two half-cells in the salt bridge? I understand how the two half-reactions work in the solutions, but the salt bridge is tripping me up. Is it just there as a solution that electrons can flow to to get to the other half-reaction, and doesn't react at all?
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Re: Chem Lab C

Post by Kokonilly »

EASTstroudsburg13 wrote:Is it just there as a solution that electrons can flow to to get to the other half-reaction, and doesn't react at all?
To my knowledge, yes.
EDIT: Sorry, I didn't know you asked this so long ago. That probably wasn't helpful.
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Re: Chem Lab C

Post by EastStroudsburg13 »

Well, I haven't competed yet, so it is kind of helpful. Thanks.
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Re: Chem Lab C

Post by Kokonilly »

So I looked this up: basically, the salt bridge serves as an electrolyte that equalizes charge between the cation and the anion.
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Re: Chem Lab C

Post by aubrey048 »

I have a really weird question...

Ok. Here goes. The Chem Lab team from my school were stumped by this station at Regionals. They gave them two unlabeled cups of Coke. One was Diet, the other regular. They were to determine which was which without tasting either sample. They guessed by smell. The team was allowed to use any material they brought in to do this (i.e litmus paper etc., I've never done Chem Lab. You guys know better than I do.). But still, they had no idea how this could be scientifically determined. Obviously there's a way or it wouldn't have been one of the stations.

Any thoughts?

I was thinking maybe regular Coke would have a higher pH than diet Coke, but I'm really just grasping at straws here.
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Re: Chem Lab C

Post by Skink »

I don't think so...both are the same except for sugar vs. aspartame. Both solutes should be relatively nonacidic, so I'm guessing the only observable difference between them is the following, though I'm not sure if you could determine this based on what was given...
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Re: Chem Lab C

Post by Tidus »

The density of those cokes should be different, as you need a lot less aspartine than sugar to make the coke sweet. That's why the can floats in the picture :D.
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