Forensics C

User avatar
pikachu4919
Moderator
Moderator
Posts: 713
Joined: December 7th, 2012, 2:30 pm
Division: Grad
State: IN
Pronouns: She/Her/Hers
Has thanked: 85 times
Been thanked: 123 times

Re: Forensics C

Post by pikachu4919 » October 9th, 2015, 3:16 pm

justgreene wrote:Can anyone refer me to a website to buy good quality plastics to test for density? I have beads but they seem to be inconsistent. For example some of the beads of HDPE float in 48% isopropyl alcohol, whereas others sink.
The ever-so-famous IN state/nationals supervisor Linda Wozniewski recommended me this: http://store.americanchemistry.com/Hand ... astics-HOP
Carmel HS (IN) '16
Purdue BioE '21
Nationals 2016 ~ 4th place Forensics


"It is important to draw wisdom from different places. If you take it from only one place, it becomes rigid and stale." -Uncle Iroh

About me || Rate my tests!
Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

MY CABBAGES!

Willows
Member
Member
Posts: 5
Joined: May 22nd, 2012, 3:13 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by Willows » October 9th, 2015, 5:44 pm

Where's a good place to get fibers and/or hairs for practice?

User avatar
pikachu4919
Moderator
Moderator
Posts: 713
Joined: December 7th, 2012, 2:30 pm
Division: Grad
State: IN
Pronouns: She/Her/Hers
Has thanked: 85 times
Been thanked: 123 times

Re: Forensics C

Post by pikachu4919 » October 10th, 2015, 11:20 am

Willows wrote:Where's a good place to get fibers and/or hairs for practice?
Those are a lot easier to come by than plastics :lol: well what I did is that for fibers, I went to the local craft store, picked out fabrics that were 100% of those particular fibers (i.e. a 100% cotton, 100% wool, 100% silk, etc.—but NO MIXTURES!! THOSE'LL THROW YOU OFF!!) and asked them for 1-inch samples of each of them. They gave me most of them for free, but idk if craft stores in your area will do the same. As for hairs...I think you could literally just pick them off actual animals and people? It sounds gross but that's how I'd do it because honestly I don't think it's really worth ordering fancy, already-prepared slides with the stuff on them since you'll probably have to prepare your own slides at competition anyways 8-)
Carmel HS (IN) '16
Purdue BioE '21
Nationals 2016 ~ 4th place Forensics


"It is important to draw wisdom from different places. If you take it from only one place, it becomes rigid and stale." -Uncle Iroh

About me || Rate my tests!
Opinions expressed on this site are not official; the only place for official rules changes and FAQs is soinc.org.

MY CABBAGES!

User avatar
Panda Weasley
Member
Member
Posts: 133
Joined: September 27th, 2014, 6:24 am
Division: C
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by Panda Weasley » October 28th, 2015, 6:36 pm

I have a plastics question. When I was in Crime Busters my 3 years ago we had plastics (last year my state didn't for some reason) and we were taught (as well as I can remember) to just put the samples in the liquids and see if they sink or float. This seems to be the typical way to do it, but I can't for the life of me remember what we did after we had that knowledge. :oops: Is there just a basic chart we compare results to? From reading previous posts in this thread I think that's the answer, but I'm still confused. Any help would be lovely! :D
DFTBA!
Events 2019: Forensics and Fossils
Proud member of Teh Ento Cult.
:ugeek:

iwonder
Admin Emeritus
Admin Emeritus
Posts: 1115
Joined: May 10th, 2011, 8:25 pm
Division: Grad
State: TX
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by iwonder » October 28th, 2015, 6:50 pm

Panda Weasley wrote:I have a plastics question. When I was in Crime Busters my 3 years ago we had plastics (last year my state didn't for some reason) and we were taught (as well as I can remember) to just put the samples in the liquids and see if they sink or float. This seems to be the typical way to do it, but I can't for the life of me remember what we did after we had that knowledge. :oops: Is there just a basic chart we compare results to? From reading previous posts in this thread I think that's the answer, but I'm still confused. Any help would be lovely! :D
Yeah, so see if they sink or float (I recommend pushing them down into the liquid and seeing how they move, surface tension is a factor). Then you'll know if they're more or less dense than that liquid, compare the densities.
'If you're the smartest person in the room, you're in the wrong room' - Unknown

vivian_t
Member
Member
Posts: 5
Joined: March 11th, 2015, 3:34 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by vivian_t » October 31st, 2015, 10:35 pm

This is my first year doing Forensics so I'm a little bit unfamiliar with some of the topics and have a few questions to ask:
  • 1. What material should we learn for pollen and seed? Or basic information about plants will do?
    2. For the glass what will I expect the proctor to ask? Figure out what is the impact, (like tracks) which two pictures match, or a combination of both?
    3. What are some methods of achieving Qualitative Analysis efficiently? You see, I did mine by testing the powders first four times in the order of Iodine<HCl<H2O<NaOH then the remaining with Benedict's Solution and the Flame Test. I couldn't find any good charts, but I did find some that tells the properties/reactiviy of each powder and base my chart on those results. Either the list of powder are hard to distinguish because some of them have so many properties in common or I'm just making this harder on my self by making the least efficient chart lol.
Thanks and any help is appreciated! :D
SciOly 2015-2016 Events:

Anatomy and Physiology
Forensics

AlphaTauri
Staff Emeritus
Staff Emeritus
Posts: 829
Joined: September 11th, 2009, 1:41 pm
Division: Grad
State: PA
Has thanked: 0
Been thanked: 0
Contact:

Re: Forensics C

Post by AlphaTauri » November 2nd, 2015, 12:06 pm

1. In my three years of competing in Forensics, I only ever saw pollen/seeds on one test (and it wasn't a particularly good test...), so I honestly don't know. Because the rules specify something like 1-3 subtopics from part e(?), most event supervisors forego it in favor of the classics like fingerprints or blood spatters. If anyone's ever seen it done well on a test, post about it, because I have no clue what one should actually study for that section.

2. Glass is a bit more commonly tested. Off the top of my head, you could be asked the order in which several cracks in a piece of glass formed, which direction the glass was shattered from, or maybe even determining the type of glass via refractive index (Snell's Law).

3. For QA, everyone has their own method, but your ultimate goal is to do as few tests as possible on each powder, so that you can be the most efficient with your time. Personally I am an ardent supporter of doing flame tests first, as it positively IDs three powders -- four, if you can distinguish the deep orange of Ca(NO3)2 from the yellow-orange of sodium -- and classifies the rest into three distinct categories (sugars (2), sodium compounds (4), and things that don't burn (5)). These categories can then be split up and the powders ID'd much more easily because there are much fewer possibilities in each. I know a lot of people also do solubility first for similar reasons, but I don't really know the full chart for that since I've never done it that way.

Hope that helps!
Hershey Science Olympiad 2009 - 2014
Volunteer for Michigan SO 2015 - 2018

]\/[ Go Blue!

josephm
Member
Member
Posts: 7
Joined: October 23rd, 2015, 6:30 pm
Division: C
State: NY
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by josephm » November 4th, 2015, 3:21 pm

It seems like Forensics is the division C equivalent to Crime Busters, but what are the main differences?
Questions are a sign of intelligence

josephm
Member
Member
Posts: 7
Joined: October 23rd, 2015, 6:30 pm
Division: C
State: NY
Has thanked: 0
Been thanked: 0

Re: Forensics C

Post by josephm » November 4th, 2015, 3:24 pm

Also what's the best way to manage time? Should both partners work on one section at a time to finish it faster or should they split up to cover more at once? And what would be the most important sections to work on first? QA obviously but then what
Questions are a sign of intelligence

User avatar
samlan16
Member
Member
Posts: 523
Joined: December 30th, 2013, 2:54 pm
Division: Grad
State: TN
Has thanked: 0
Been thanked: 0
Contact:

Re: Forensics C

Post by samlan16 » November 4th, 2015, 6:35 pm

josephm wrote:It seems like Forensics is the division C equivalent to Crime Busters, but what are the main differences?
This is how I put it to the middle schoolers I coach: in Crime Busters, you only light fibers on fire. In Forensics, you light everything* on fire. That pretty much means that you are now taking advantage of basic spectroscopy to identify your compounds. Also, there are no metals or liquids, physical evidence is more in depth, and you will be expected to learn how to read a mass spec.
josephm wrote:Also what's the best way to manage time? Should both partners work on one section at a time to finish it faster or should they split up to cover more at once? And what would be the most important sections to work on first? QA obviously but then what
Split up, but reconvene early enough to write the essay.
EDIT: It really depends on the test and your preferences, but do try to get Benedict's testing and chromatography done early enough to correct any problems that may arise.



*Except plastics.
Remember, we are proud of every team that participated and you are all winners.

Locked

Return to “2016 Lab Events”

Who is online

Users browsing this forum: No registered users and 1 guest