Crime Busters B

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Crimesolver
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Re: Crime Busters B

Post by Crimesolver » February 7th, 2019, 6:19 pm

CPScienceDude wrote:1. What Powder has a pH of 6 and turns I2 blue?
2. Describe the difference in appearance of dog and cat hair while under a microscope.
3. You are given a plastic. It sinks in water, 10% NaCl, and saturated NaCl. You notice it it is rubbery. What is this plastic?
1. In my experience, flour turns pretty green, so imma say cornstarch.
2. Dog has a continuous medulla, while cat has broken up medulla 
3. PETE (?)
Keep on going :)

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Re: Crime Busters B

Post by CPScienceDude » February 7th, 2019, 6:40 pm

Crimesolver wrote:
CPScienceDude wrote:1. What Powder has a pH of 6 and turns I2 blue?
2. Describe the difference in appearance of dog and cat hair while under a microscope.
3. You are given a plastic. It sinks in water, 10% NaCl, and saturated NaCl. You notice it it is rubbery. What is this plastic?
1. In my experience, flour turns pretty green, so imma say cornstarch.
2. Dog has a continuous medulla, while cat has broken up medulla 
3. PETE (?)
1. Flour. https://www.youtube.com/watch?v=LnRx3nrKB8c
2. yup
3. I was thinking PVC. " PVC is in the glassy state at room temperature but is a special case because it can be easily modified to be rubbery by the addition of plasticizers." From http://www.appstate.edu/~clementsjs/polymerproperties/plastics_low_temp.pdf
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Re: Crime Busters B

Post by Crimesolver » February 7th, 2019, 9:04 pm

CPScienceDude wrote:
1. Flour. https://www.youtube.com/watch?v=LnRx3nrKB8c
2. yup
3. I was thinking PVC. " PVC is in the glassy state at room temperature but is a special case because it can be easily modified to be rubbery by the addition of plasticizers." From http://www.appstate.edu/~clementsjs/polymerproperties/plastics_low_temp.pdf
Hmm, interesting -

1. What does AFIS stand for?
2. What is the most common type of fingerprint?
3. What is the difference between aluminum and magnesium?
Keep on going :)

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Re: Crime Busters B

Post by CPScienceDude » February 8th, 2019, 11:01 am

Crimesolver wrote:
Hmm, interesting -

1. What does AFIS stand for?
2. What is the most common type of fingerprint?
3. What is the difference between aluminum and magnesium?
1. Automated Fingerprint Identification System
2. Loop?
3. Magnesium reacts with water?
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Re: Crime Busters B

Post by Anapolis » February 13th, 2019, 6:10 pm

CPScienceDude wrote:
Crimesolver wrote:
Hmm, interesting -

1. What does AFIS stand for?
2. What is the most common type of fingerprint?
3. What is the difference between aluminum and magnesium?
1. Automated Fingerprint Identification System
2. Loop?
3. Magnesium reacts with water?
i agree with everything but 3, i never really used water to react with metals (its kinda a waste of time imo because most of the metals on the list have no reaction with water, and if there is it is minimal) i would say that in HCl aluminum is usually covered in small bubbles and in comparison, magnesium reacts quite violently
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Re: Crime Busters B

Post by Crimesolver » February 13th, 2019, 6:28 pm

Anapolis wrote:
CPScienceDude wrote:
Crimesolver wrote:
Hmm, interesting -

1. What does AFIS stand for?
2. What is the most common type of fingerprint?
3. What is the difference between aluminum and magnesium?
1. Automated Fingerprint Identification System
2. Loop?
3. Magnesium reacts with water?
i agree with everything but 3, i never really used water to react with metals (its kinda a waste of time imo because most of the metals on the list have no reaction with water, and if there is it is minimal) i would say that in HCl aluminum is usually covered in small bubbles and in comparison, magnesium reacts quite violently
yeah, you're point is correct. I personally don't use that method either, but many of the tests I take would usually determine the difference between aluminum and magnesium through the reaction in water.
Keep on going :)

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Re: Crime Busters B

Post by Rivkaaa » March 4th, 2019, 2:55 pm

1. What's the difference in dog and cat hair under a microscope?
2. How do you tell apart calcium carbonate and baking soda?
3. How do you distinguish a synthetic fiber from an animal fiber by smell (burn test)?
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Re: Crime Busters B

Post by wec01 » March 4th, 2019, 4:51 pm

Rivkaaa wrote:1. What's the difference in dog and cat hair under a microscope?
2. How do you tell apart calcium carbonate and baking soda?
3. How do you distinguish a synthetic fiber from an animal fiber by smell (burn test)?
1. The cortex of the cat hair tends to be more divided/segmented than that of dog hair
2. Baking soda is basic while calcium carbonate is neutral
3. Synthetic fibers tend to smell somewhat sweet while animal fibers smell more putrid, like burning hair (because that's what it is)
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Re: Crime Busters B

Post by Rivkaaa » March 7th, 2019, 5:13 pm

wec01 wrote:
Rivkaaa wrote:1. What's the difference in dog and cat hair under a microscope?
2. How do you tell apart calcium carbonate and baking soda?
3. How do you distinguish a synthetic fiber from an animal fiber by smell (burn test)?
1. The cortex of the cat hair tends to be more divided/segmented than that of dog hair
2. Baking soda is basic while calcium carbonate is neutral
3. Synthetic fibers tend to smell somewhat sweet while animal fibers smell more putrid, like burning hair (because that's what it is)
1. Yes, but also, dog hair has ovoid bodies, while cat hair tends to have "scales." Dog hair has a thicker medulla (around 2/3), while cat hair has a medulla of <1/3. 2. Yep!
3. Definitely!
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Re: Crime Busters B

Post by wec01 » March 8th, 2019, 8:00 am

1. What is the most common fingerprint type (between loops, arches and whorls)?
2. List three fingerprint development techniques.
3. What is the difference between patent, latent, and plastic fingerprints?
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