Forensics C

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Forensics C

Postby bernard » Fri Jun 17, 2016 5:00 am

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Re: Forensics C

Postby Magikarpmaster629 » Fri Sep 09, 2016 12:54 am

I got my rules, and there are two changes. One is that they replaced cat and dog hair with cow and squirrel hair. The other is that we are no longer allowed a binder :cry: and can only bring five double sided sheets of paper.
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Re: Forensics C

Postby Unome » Fri Sep 09, 2016 12:57 am

Magikarpmaster629 wrote:no longer allowed a binder

IMO you should be celebrating. It means event sups are less likely to ask random off-the-cuff fact-based questions, plus five sheets is (in my limited experience) more than enough for any event.
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Re: Forensics C

Postby daydreamer0023 » Sat Sep 10, 2016 8:08 pm

Unome wrote:
Magikarpmaster629 wrote:no longer allowed a binder

IMO you should be celebrating. It means event sups are less likely to ask random off-the-cuff fact-based questions, plus five sheets is (in my limited experience) more than enough for any event.

Ah, well. Suppose that's better than a single cheat sheet from a couple years ago. Meanwhile, cow and squirrel hair...anyone got any pictures on that?
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Re: Forensics C

Postby Panda Weasley » Sun Sep 11, 2016 2:06 am

daydreamer0023 wrote:
Unome wrote:
Magikarpmaster629 wrote:no longer allowed a binder

IMO you should be celebrating. It means event sups are less likely to ask random off-the-cuff fact-based questions, plus five sheets is (in my limited experience) more than enough for any event.

Ah, well. Suppose that's better than a single cheat sheet from a couple years ago. Meanwhile, cow and squirrel hair...anyone got any pictures on that?

I was so confused when I heard they switched those two hairs. I guess not everyone has easy access to cows and squirrels. :lol:
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Re: Forensics C

Postby Magikarpmaster629 » Sun Sep 11, 2016 12:05 pm

Panda Weasley wrote:
daydreamer0023 wrote:
Unome wrote:IMO you should be celebrating. It means event sups are less likely to ask random off-the-cuff fact-based questions, plus five sheets is (in my limited experience) more than enough for any event.

Ah, well. Suppose that's better than a single cheat sheet from a couple years ago. Meanwhile, cow and squirrel hair...anyone got any pictures on that?

I was so confused when I heard they switched those two hairs. I guess not everyone has easy access to cows and squirrels. :lol:

There are pictures on google images. I haven't looked up how hard it is to get them, but I think there's a good chance we won't see them until MIT or nationals.
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Re: Forensics C

Postby sciduck » Sun Oct 16, 2016 3:12 pm

Magikarpmaster629 wrote:
Panda Weasley wrote:
daydreamer0023 wrote:Ah, well. Suppose that's better than a single cheat sheet from a couple years ago. Meanwhile, cow and squirrel hair...anyone got any pictures on that?

I was so confused when I heard they switched those two hairs. I guess not everyone has easy access to cows and squirrels. :lol:

There are pictures on google images. I haven't looked up how hard it is to get them, but I think there's a good chance we won't see them until MIT or nationals.


Haha, it took me weeks to find squirrel and cow hairs. If you really need them I would buy squirrel brushes. Apparently every Russian artist I know has them, but you can also buy them online: http://www.dickblick.com/products/blick-studio-natural-squirrel-brushes/ https://www.amazon.com/s/ref=nb_sb_noss_1/167-1389812-3310211?url=search-alias%3Daps&field-keywords=squirrel+brush As for cow hairs, I asked the same farmers who gave me horse hair last year.
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Re: Forensics C

Postby daydreamer0023 » Sun Oct 16, 2016 9:50 pm

Just wondering, is salt the only powder with a cubic crystal? Silly question, I know. :P
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Re: Forensics C

Postby Magikarpmaster629 » Mon Oct 17, 2016 12:53 am

daydreamer0023 wrote:Just wondering, is salt the only powder with a cubic crystal? Silly question, I know. :P

I don't think crystal shape works well for IDing powders, although I haven't tried much. I think they're extremely variable, and lack of consistency makes it hard to ID. I would think that at least KCl would also have a cubic structure, since it's very similar chemically to NaCl.
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Re: Forensics C

Postby pikachu4919 » Wed Oct 26, 2016 4:01 am

Magikarpmaster629 wrote:
daydreamer0023 wrote:Just wondering, is salt the only powder with a cubic crystal? Silly question, I know. :P

I don't think crystal shape works well for IDing powders, although I haven't tried much. I think they're extremely variable, and lack of consistency makes it hard to ID. I would think that at least KCl would also have a cubic structure, since it's very similar chemically to NaCl.


Yeah I mean considering the national supervisor's description of sodium acetate is "very fine white powder" and the sample of sodium acetate we had at our school was medium-sized clear crystals, I'd say really don't rely on the physical appearance of the powder as a key identifier. There are plenty of other ones you can use that are far more robust.
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Re: Forensics C

Postby daydreamer0023 » Thu Oct 27, 2016 2:15 am

pikachu4919 wrote:
Magikarpmaster629 wrote:
daydreamer0023 wrote:Just wondering, is salt the only powder with a cubic crystal? Silly question, I know. :P

I don't think crystal shape works well for IDing powders, although I haven't tried much. I think they're extremely variable, and lack of consistency makes it hard to ID. I would think that at least KCl would also have a cubic structure, since it's very similar chemically to NaCl.


Yeah I mean considering the national supervisor's description of sodium acetate is "very fine white powder" and the sample of sodium acetate we had at our school was medium-sized clear crystals, I'd say really don't rely on the physical appearance of the powder as a key identifier. There are plenty of other ones you can use that are far more robust.


I haven't looked at crystals structure a lot, but I knew from CB that one of the key features of salt was cubic crystals, so I was kind of going to use it as more of a verification of the correct powder than an identifier.
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Re: Forensics C

Postby moumantai » Fri Nov 11, 2016 4:49 pm

Hi guys! Just wanted to check in. This is my first year doing Forensics. I'm in first-year chemistry and my partner is in AP Chemistry. I'm really excited to give this event a shot; Is there any rule-of-thumb advice we can get?

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Re: Forensics C

Postby Panda Weasley » Fri Nov 11, 2016 7:29 pm

moumantai wrote:Hi guys! Just wanted to check in. This is my first year doing Forensics. I'm in first-year chemistry and my partner is in AP Chemistry. I'm really excited to give this event a shot; Is there any rule-of-thumb advice we can get?

Not really "rule-of-thumb" worthy, but my advice to you is to repeatedly practice IDing everything. Once you feel familiar with everything give each other unknowns to identify. If you don't have a lot of time to prepare, focus on the powders as they are worth the most points.
I hope this was helpful, good luck! :D

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Re: Forensics C

Postby pikachu4919 » Tue Nov 15, 2016 7:33 am

Panda Weasley wrote:
moumantai wrote:Hi guys! Just wanted to check in. This is my first year doing Forensics. I'm in first-year chemistry and my partner is in AP Chemistry. I'm really excited to give this event a shot; Is there any rule-of-thumb advice we can get?

Not really "rule-of-thumb" worthy, but my advice to you is to repeatedly practice IDing everything. Once you feel familiar with everything give each other unknowns to identify. If you don't have a lot of time to prepare, focus on the powders as they are worth the most points.
I hope this was helpful, good luck! :D


Panda Weasley is spot on that lots and lots of practice on the lab practical is the best way to prepare for Forensics. But I'd also say to try to practice polymer ID just as much as powder ID because it can also count for a lot of points. And I say "try" because it's definitely slightly more difficult to access practice versions of the polymers than the powders. I mean powder ID is hard because messing up by contamination is pretty darn easy to do but polymer ID is also hard because while the indicator tests are shorter and not as easy to mess up, you still have three different types of polymers that you have to handle, each with its own set of unique ways to ID each. (When I competed, my partner did powders and I did polymers and my partner found polymer ID hard for her and I found powder ID hard for myself so...yeah) For example, the most recent national exam, there were 14 powders to ID worth 3 pts each but there were also 18 total polymers to ID also worth 3 pts each. Not every test is structured exactly like that but the fact that there is a broader range of possible polymers than possible powders also means there might be more polymers than powders on the exams. Also, never forget the trivia/essay. Those are (somewhat) easy points (most of the time, unless it's nationals when you have a boatload of them that you have to juggle along with the ID's and chromatography and all that jazz) that can help your score out a lot in the case that your ID's go awry.

The TL;DR version:
Powder ID is important, and you should practice it a ton. But don't focus on it so much that you sacrifice all the other parts of the exam, especially polymer ID.

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Re: Forensics C

Postby Lumitailz » Mon Nov 21, 2016 7:59 pm

For Powder ID, do supervisors usually provide anhydrous or hydrated powders? (Normally I ID magnesium sulfate just by its appearance, but if they give me anhydrous then I would be stumped :D )


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