Crime Busters B

[amk578]

Cool!

1. What is the most common fingerprint?
2. What does AFIS stand for?
3. What is the only acidic powder? What is its chemical formula?
4. You are given a mixture that is slightly tan in color. When you place drops of water on it, the water kind of gels up. Then, you pour a few drops of HCl into the mixture and there is fizzing for almost a minute. What are the two substances that composes the mixture?
5. What polymer floats in water and is not translucent?

[ledwards003]

Cool!

1. What is the most common fingerprint?
2. What does AFIS stand for?
3. What is the only acidic powder? What is its chemical formula?
4. You are given a mixture that is slightly tan in color. When you place drops of water on it, the water kind of gels up. Then, you pour a few drops of HCl into the mixture and there is fizzing for almost a minute. What are the two substances that composes the mixture?
5. What polymer floats in water and is not translucent?

Can I try my hand at this?
1. Loops are the most common fingerprint
2. IAFIS (I am assuming that is what you meant because I do not know otherwise) stands for Integrated Automated Fingerprint Identification System
3. Vitamin C, with chemical formula C6H8O6
4. Gelatin is the first and... calcium carbonate? (sorry, I typically pay attention to solubility rather than how long the fizz lasts)
5. Would this be polystyrene?

[amk578]

Cool!

1. What is the most common fingerprint?
2. What does AFIS stand for?
3. What is the only acidic powder? What is its chemical formula?
4. You are given a mixture that is slightly tan in color. When you place drops of water on it, the water kind of gels up. Then, you pour a few drops of HCl into the mixture and there is fizzing for almost a minute. What are the two substances that composes the mixture?
5. What polymer floats in water and is not translucent?

Can I try my hand at this?
1. Loops are the most common fingerprint
2. IAFIS (I am assuming that is what you meant because I do not know otherwise) stands for Integrated Automated Fingerprint Identification System
3. Vitamin C, with chemical formula C6H8O6
4. Gelatin is the first and... calcium carbonate? (sorry, I typically pay attention to solubility rather than how long the fizz lasts)
5. Would this be polystyrene?

1. Correct
2. Correct
3. Correct
4. Gelatin is right, but I was thinking baking soda because it is notorious for fizzing continuously
5. No, PS doesn't float in water, the correct answer is polypropylene

Your turn!

[CPScienceDude]

I'll kick this back up again.
1. What plastic half sinks half floats in water?
2. When burned, this synthetic fiber produces a hard black bead, and when withdrawn it stops burning. What is this fiber?
3. This powder has a pH of 2, and turns Iodine clear. What is this powder?
4. You determine a liquid to be either hydrogen peroxide or water. How do you tell the difference?

[jimmy-bond]

I'll kick this back up again.
1. What plastic half sinks half floats in water?
2. When burned, this synthetic fiber produces a hard black bead, and when withdrawn it stops burning. What is this fiber?
3. This powder has a pH of 2, and turns Iodine clear. What is this powder?
4. You determine a liquid to be either hydrogen peroxide or water. How do you tell the difference?

Answers? (Click to Show Hidden Text)

1. Polystyrene
2. Spandex
3. Vitamin C
4. Shake to see if bubbles form

[CPScienceDude]

I'll kick this back up again.
1. What plastic half sinks half floats in water?
2. When burned, this synthetic fiber produces a hard black bead, and when withdrawn it stops burning. What is this fiber?
3. This powder has a pH of 2, and turns Iodine clear. What is this powder?
4. You determine a liquid to be either hydrogen peroxide or water. How do you tell the difference?

Answers? (Click to Show Hidden Text)

1. Polystyrene
2. Spandex
3. Vitamin C
4. Shake to see if bubbles form

Correct. But... (Click to Show Hidden Text)

1. Yup
2. I was thinking Nylon, but I'm not sure if Spandex fits the bill too. Maybe, but idk.
3. Yup
4. That's one way but Iodine helps too. Iodine in hydrogen peroxide bubble after almost a minute.

[jimmy-bond]

Correct. But... (Click to Show Hidden Text)

1. Yup
2. I was thinking Nylon, but I'm not sure if Spandex fits the bill too. Maybe, but idk.
3. Yup
4. That's one way but Iodine helps too. Iodine in hydrogen peroxide bubble after almost a minute.

For #4, I tend to essentially sprint through ID so I use the shake test. It takes a literal 2 seconds, but sometimes water gets fairly bubbly, so it isn't the most efficient I admit.

Questions (Click to Show Hidden Text)

1. Describe the use of ninhydrin to develop fingerprints.
2. Name a solution that can be used in a float test to differentiate HDPE and LDPE.
3. What is the thickest layer in a strand of hair?

[CPScienceDude]

Answers (Click to Show Hidden Text)

1. It reacts with the amino acids and turns a dark blue/purple.
2. 46% Isopropyl Alcohol
3. The cortex

[jimmy-bond]

Answers (Click to Show Hidden Text)

1. It reacts with the amino acids and turns a dark blue/purple.
2. 46% Isopropyl Alcohol
3. The cortex

Correct. Your turn.

[CPScienceDude]

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?