Forensics C

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poparteeb2
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Re: Forensics C

Post by poparteeb2 »

Can anyone help me with the two powders that are supposed to form precipitates w/ NaOH?
Calcium nitrate and magnesium sulfate? I think I have really bad samples at school or something, because neither of them are forming precipitates.
And how do you tell the difference between the two if you don't have a flame test? Do they react differently with the reagents given or have different pH? Or do the precipitates look different?
Sorry it's a lot of questions! I'll be really glad if anyone with Forensics experience can help out :)
Regionals: 1st place Crime, 1st place Anatomy, 3rd place Experimental Design.
States: 1st Place Anatomy, 2nd Place Experimental Design, 6th Place Crime, 26th Place Powders *wince*
Nationals: 4th place Anatomy, 4th place Crime, 30th Powders *wince again*
Overall team ranking: 7th
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Re: Forensics C

Post by pikachu4919 »

poparteeb2 wrote:Can anyone help me with the two powders that are supposed to form precipitates w/ NaOH?
Calcium nitrate and magnesium sulfate? I think I have really bad samples at school or something, because neither of them are forming precipitates.
And how do you tell the difference between the two if you don't have a flame test? Do they react differently with the reagents given or have different pH? Or do the precipitates look different?
Sorry it's a lot of questions! I'll be really glad if anyone with Forensics experience can help out :)
Hmmm ... well not all forms of any of the powders are the same ... so that could be a factor. Also, Ca(NO3) has an orange flame test that gives off sparks, unlike MgSO4 that does not burn, but may give off water vapor.

As for distinguishing powders, I've found that pH helps quite often, and maybe conductivity or flame tests. Then there's everything else as well.
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Nationals 2016 ~ 4th place Forensics


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Re: Forensics C

Post by computergeek3 »

Does anyone know what the most commonly used density solutions (for plastic ID) are?
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Re: Forensics C

Post by JustDroobles »

computergeek3 wrote:Does anyone know what the most commonly used density solutions (for plastic ID) are?
Check out the wiki page for Forensics. http://scioly.org/wiki/index.php/Forensics#Polymers
Common liquids used to test plastic densities include water, vegetable oil, isopropyl alcohol, and NaCl solution (10%, 25%, and saturated).
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Re: Forensics C

Post by Skyrenify »

I was wondering how one would do hair follicle analysis because we had it in states last year and my teammate and I didn't know how to find out which organism it belonged to. I'm trying to cover all my bases so I will be able to avoid being dumbfounded during the event. Last year went well, but really want to make a place for my High School this year.
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Re: Forensics C

Post by JustDroobles »

Skyrenify wrote:I was wondering how one would do hair follicle analysis because we had it in states last year and my teammate and I didn't know how to find out which organism it belonged to. I'm trying to cover all my bases so I will be able to avoid being dumbfounded during the event. Last year went well, but really want to make a place for my High School this year.
The two major features for hair ID are the medulla and cuticle pattern.

Human hair has a thin and often non-continuous medulla and an imbricate cuticle pattern.
Dog hair has a thick medulla and an imbricate scale pattern.
Cat hair has spinous cuticle pattern.
Bat hair has a coronal cuticle pattern.

If you don't know what any of these terms mean, they should be easily Google-able.
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Re: Forensics C

Post by Skyrenify »

JustDroobles wrote:
Skyrenify wrote:I was wondering how one would do hair follicle analysis because we had it in states last year and my teammate and I didn't know how to find out which organism it belonged to. I'm trying to cover all my bases so I will be able to avoid being dumbfounded during the event. Last year went well, but really want to make a place for my High School this year.
The two major features for hair ID are the medulla and cuticle pattern.

Human hair has a thin and often non-continuous medulla and an imbricate cuticle pattern.
Dog hair has a thick medulla and an imbricate scale pattern.
Cat hair has spinous cuticle pattern.
Bat hair has a coronal cuticle pattern.

If you don't know what any of these terms mean, they should be easily Google-able.
Ahh thank you!

Might be able to get that elusive 1st place this year.
Still beating myself up for mixing up common blood types last year at states. Got us 4th place T^T

Anyhow, thank you very much :D
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Re: Forensics C

Post by JustDroobles »

Skyrenify wrote:
JustDroobles wrote:
Skyrenify wrote:I was wondering how one would do hair follicle analysis because we had it in states last year and my teammate and I didn't know how to find out which organism it belonged to. I'm trying to cover all my bases so I will be able to avoid being dumbfounded during the event. Last year went well, but really want to make a place for my High School this year.
The two major features for hair ID are the medulla and cuticle pattern.

Human hair has a thin and often non-continuous medulla and an imbricate cuticle pattern.
Dog hair has a thick medulla and an imbricate scale pattern.
Cat hair has spinous cuticle pattern.
Bat hair has a coronal cuticle pattern.

If you don't know what any of these terms mean, they should be easily Google-able.
Ahh thank you!

Might be able to get that elusive 1st place this year.
Still beating myself up for mixing up common blood types last year at states. Got us 4th place T^T

Anyhow, thank you very much :D
No problem! And I know how you feel, I got 2nd place in Forensics my junior and senior year... I was actually super excited junior year because the highest placing I had gotten throughout the season was a 4th place at an invitational. However, after getting several invitational golds my senior year I was hoping for that tiny improvement at state. I hope you get that elusive gold this year!
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Re: Forensics C

Post by Skyrenify »

JustDroobles wrote: No problem! And I know how you feel, I got 2nd place in Forensics my junior and senior year... I was actually super excited junior year because the highest placing I had gotten throughout the season was a 4th place at an invitational. However, after getting several invitational golds my senior year I was hoping for that tiny improvement at state. I hope you get that elusive gold this year!
Haha thanks!

I'm really good at winging things :p
For example, I made my Boomilever the day before the competition (regionals were 1 day ago) using a bansaw and some gorilla glue and 5 sticks of balsa. Somehow, every other star team broke a parameter and I got hold of 2nd.
I did Forensics in states last year as a freshman and it was traumatic. There was a pile of samples that I couldn't even fathom to identify in the allotted time. Some how I managed to place but it cost me my nose as I sniffed all the substances. (ammonia).
I really want to get rid of relying on luck and do something with real preparation.

Also, another quick question,
Can we have handwritten notes on the note sheet that we can bring?
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Re: Forensics C

Post by pikachu4919 »

Is the formula for Benedicts Reagent CuSO4+NaOH or CuSO4+5H2O? sorry I've seen both and idk which one is correct or if neither is correct ...
Carmel HS (IN) '16
Purdue BioE '21? reevaluating my life choices
Nationals 2016 ~ 4th place Forensics


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