Forensics C
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Re: Forensics C
This test is located in the test exchange: http://www.scioly.org/wiki/images/3/3a/ ... Test_3.pdf
I was wondering if anyone had the answer key to this test? If so, that'd be great!
I was wondering if anyone had the answer key to this test? If so, that'd be great!
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Re: Forensics C
Another question:
What's a good way to differentiate PETE, PVC, PC, and PMMA? All of their densities are greater than that of a saturated NaCl solution(PMMA and PC are approximately equal). My teacher mentioned that stepping on a sample of PC and PMMA would be a good way to differentiate those, because of how they react to force. I believe PC will crack whereas PMMA will shatter into smaller pieces (though I am not 100% sure). How would I differentiate PETE and PVC? Would I have to rely on burn test results?
What's a good way to differentiate PETE, PVC, PC, and PMMA? All of their densities are greater than that of a saturated NaCl solution(PMMA and PC are approximately equal). My teacher mentioned that stepping on a sample of PC and PMMA would be a good way to differentiate those, because of how they react to force. I believe PC will crack whereas PMMA will shatter into smaller pieces (though I am not 100% sure). How would I differentiate PETE and PVC? Would I have to rely on burn test results?
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Re: Forensics C
Usually I distinguish PC and PMMA from 25% NaCl (which has a density of ~1.19 g/cm^3, provided that it's made correctly, so PC will sink and PMMA will float). I've never heard of stepping on it to differentiate them, but it sounds like an interesting thing to do For PETE and PVC, you are correct in that you have to rely on burn test results, and supervisors will provide those if they're necessary to tell the difference.JT016 wrote:Another question:
What's a good way to differentiate PETE, PVC, PC, and PMMA? All of their densities are greater than that of a saturated NaCl solution(PMMA and PC are approximately equal). My teacher mentioned that stepping on a sample of PC and PMMA would be a good way to differentiate those, because of how they react to force. I believe PC will crack whereas PMMA will shatter into smaller pieces (though I am not 100% sure). How would I differentiate PETE and PVC? Would I have to rely on burn test results?
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- Magikarpmaster629
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Re: Forensics C
So does the ES give salt in a solution or as crystals for plastic density tests?
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Re: Forensics C
Usually the ES has all of the solutions already set up (meaning you can't make your own). I have never seen or heard of a time when competitors had to make the solutions.Magikarpmaster629 wrote:So does the ES give salt in a solution or as crystals for plastic density tests?
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Events 2019: Forensics and Fossils
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Re: Forensics C
Okay. Do they tell you the concentrations of the solutions or do you have to guess based on the plastics?Panda Weasley wrote:Usually the ES has all of the solutions already set up (meaning you can't make your own). I have never seen or heard of a time when competitors had to make the solutions.Magikarpmaster629 wrote:So does the ES give salt in a solution or as crystals for plastic density tests?
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Re: Forensics C
When they have density testing set up, yes.Magikarpmaster629 wrote:Okay. Do they tell you the concentrations of the solutions or do you have to guess based on the plastics?Panda Weasley wrote:Usually the ES has all of the solutions already set up (meaning you can't make your own). I have never seen or heard of a time when competitors had to make the solutions.Magikarpmaster629 wrote:So does the ES give salt in a solution or as crystals for plastic density tests?
But keep in mind that not every ES will provide materials for density testing, so you will need to rely on any information given about burn test results.
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Re: Forensics C
What am I looking for in NaOH tests? There doesn't seem to be much going on...
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Re: Forensics C
Try reacting MgSO4 with NaOH- a precipitate of Na2SO4 should result.Magikarpmaster629 wrote:What am I looking for in NaOH tests? There doesn't seem to be much going on...
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Re: Forensics C
You mean a Mg(OH)2 precip, right? Oh, adding onto that, Ca(NO)3 can also precip to form Ca(OH)2, which is also known as lime (not the fruit - if you've ever heard of limewater, that's a component of it), but the Mg(OH)2 is generally a lot more gel-looking and solid than the Ca(OH)2, which is more powdery although it still forms a settling solid. This is because Mg(OH)2 is completely insoluble while Ca(OH)2 is marginally soluble.samlan16 wrote:Try reacting MgSO4 with NaOH- a precipitate of Na2SO4 should result.Magikarpmaster629 wrote:What am I looking for in NaOH tests? There doesn't seem to be much going on...
Carmel HS (IN) '16
Purdue BioE '21? reevaluating my life choices
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
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Purdue BioE '21? reevaluating my life choices
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
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