Chem Lab C

peoneill
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Re: Chem Lab C

Post by peoneill »

In 2002 at nationals (the 2010 rules are a copy paste of the 2002 rules) we were given a spectrophotometer and one solution with a known concentration as well as one with an unknown concentration.

First we mixed up reference solutions of multiple concentrations using the known solution. Then we spectrophotometerized 'em and made a standard "curve" (which is not so much a curve as it is a completely straight line...) by plotting absorbancies with respect to concentration. Then we spectrophotometerized the unknown solution and figured out it's concentration from our standard curve. Then they asked us to determine the value and units of the molar absorbtivity constant.
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Re: Chem Lab C

Post by tmanneo »

Wow, Chem Lab doesn't look too bad. I love getting practice for these labs through my AP Chem class. The lab before the last lab I did was Beer's Law, and I used all the absorbencies and such. The annoying thing was making the dilution though. I had no clue what ratio to use first.

What exactly do they mean by the first lab? "Use the concept of density to experimentally determine the concentration of a solution?"
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Re: Chem Lab C

Post by peoneill »

Concentration and density are not independent functions: therefore one can be used to determine the other. As density is easy to directly measure and concentration is difficult to directly measure, that's a useful relationship.

I assure you this is one of the more difficult sets of rules for chemistry lab. There's a lot of room for wicked hard questions in both topics, much MUCH more difficult than dilution ratios and density labs - make sure you're fully digesting those rules. An AP level textbook will present excellent prep if you do the kinetics and solution chemistry chapters thoroughly (or whatever they call the chapter with colligative properties).
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Re: Chem Lab C

Post by winneratlife »

My team just lost their member for this event, so I'm considering taking it. Problem: Invitational is Saturday.
1. Do you think I can do this, or should I just let someone else? (I have a really minor chem background, but it seems I'm the only one with any work ethic at all on this team (after break, there were like 3 people out of 30 who had even started studying.)
And, 2., if I should take this event, does anybody know a place were I can get a crash course?

EDIT: Haha, got stuck doing it anyways...
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Re: Chem Lab C

Post by Flavorflav »

What are some of the labs people are running into at invitationals? Anything unexpected?
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Re: Chem Lab C

Post by pirate_capn38 »

peoneill wrote:In 2002 at nationals (the 2010 rules are a copy paste of the 2002 rules) we were given a spectrophotometer and one solution with a known concentration as well as one with an unknown concentration.

First we mixed up reference solutions of multiple concentrations using the known solution. Then we spectrophotometerized 'em and made a standard "curve" (which is not so much a curve as it is a completely straight line...) by plotting absorbancies with respect to concentration. Then we spectrophotometerized the unknown solution and figured out it's concentration from our standard curve. Then they asked us to determine the value and units of the molar absorbtivity constant.
I was wondering if anyone knows if the national tests from 2002 are available somewhere... it'd be a good study resource.
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Re: Chem Lab C

Post by peoneill »

They're out there somewhere... what a wild goose chase that will be. My guess is you'd find it in the 2003 Event Test Packet that was published by Science Oylmpiad, Inc. in 2003 (!!!). I feel... old.
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Re: Chem Lab C

Post by pirate_capn38 »

Hm... We have the 2003 test packet, but it doesn't seem to have reaction rates... Thanks a ton though, I'll keep looking!
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Re: Chem Lab C

Post by Faythe »

Lolololol i did INCREDIBLE at chem lab at our invitational! (I'm being sarcastic) We drew pictures of elk and at the top we wrote that we like the judge's beard and they're our best friends. Lol. The funny thing is we didn't get last. Our team ended up getting 3rd over all which is cool though. And there were a lot of really smart teams there.
I'm incredible at write it do it, I've been in science olympiad for four years, science olympiad is a lot of fun thoughhh haha.
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Re: Chem Lab C

Post by masterhat »

At one invitational we did a really fun iodination of acetone psuedo-first order rate law lab where we had to determine the law and constant. Even though we werent supposed to get this type of lab until state it was a good learning experience
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