Crime Busters B

[geminicross]

You should be able to find Quia (is that what it's called?) Flashcards on the internet, with brief descriptions of the powders and fibers...

Most of what you need is on the wiki


(and yes Div B has LOTS of emphasis on fibers)

But REMEMBER: ALWAYS write the essay, though it is generally the last thing people do, scribbling down a random conclusion at the last minute can be really catastrophic, a well thought or well written essay can really help you qualify (even if you screw up a portion). From what I've seen, several teams that aren't very experienced will spend ago much time on identification, that they don't even think about the essay.

[caseyotis]

You should be able to find Quia (is that what it's called?) Flashcards on the internet, with brief descriptions of the powders and fibers...

Most of what you need is on the wiki


(and yes Div B has LOTS of emphasis on fibers)

But REMEMBER: ALWAYS write the essay, though it is generally the last thing people do, scribbling down a random conclusion at the last minute can be really catastrophic, a well thought or well written essay can really help you qualify (even if you screw up a portion). From what I've seen, several teams that aren't very experienced will spend ago much time on identification, that they don't even think about the essay.

I think Quia requires membership, and ain't nobody got time fo' dat.
I saw the charts and stuff.

Okay, thank you!

I will probably need to practice that. I'm pretty sure my partner isn't the best writer, so I'll make sure to do that. I'll practice for speed so I can have time to write the essay.

[geminicross]

There are public sets that ya don't need membership to view.

And you're welcome
Good luck at states!

[caseyotis]

There are public sets that ya don't need membership to view.

And you're welcome
Good luck at states!

Eh. Too lazy.
Thank you! It's my first time going, so I hope I do well. I don't want to set my expectations too high, though.

[geminicross]

Last year was my first time also (unless Div. A counts)
But we didn't qualify this year (missed by 1 place, but we always get in by 1 place or miss by one so :/, and it's often 1 point)

But states is really fun, though Crime Busters did not go well

Polymers also isn't generally that big (it's seldom been on any of my tests) but it'd most likely appear at the state level !

[caseyotis]

Oh, awesome! You're really good, then. I don't have high expectations.

I just want to have fun with the event, but also know what I'm doing. I don't expect to medal.

Okay, thank you~ I'm going to brief through all of them (plastics, powders, polymers, etc.), then, if I have time, go deeper.

[Soccer_Girl]

I have a question. For blood splatters, do we have to identify if it was from a gun shot or a cut and that stuff? If so, how in the world are we supposed to do that??? Thanks so much!

[theriddler]

I just wanted to ask: how exactly do you test the plastics? That was one place we didn't do well at one of our invitationals.

Don't feel bad... You're not alone! First, let's discuss the theoretical intent... Supposedly, each polymer has a specific density, ranging from around .90 grams / cm3 to as much as 1.49 grams / cm3. The E/C should have at least 5 different liquids, each with different densities. These liquids, list from least dense to most dense are vegetable oil (.885 grams / cm3), 46% alcohol (.915 grams / cm3), fresh water (1.00 grams / cm3), 10% salt (1.10 grams / cm3), and 20% salt (1.16 grams / cm3). by placing a sample of the polymer in the various liquids and determining if it floats or sinks you should be able to determine the the specific density range between two liquids... In other words, if it sinks in 46% alcohol, but floats in water, you know that it must be between .915 and 1.0 density, right? That should really narrow down the possibilities. It's not fool proof... not all polymer samples, even of the same material, have the same density, they vary... also, they can have this very irritating tendency to have air bubbles adhere to them, really screwing the whole thing up, floating when they should be sinking. ALWAYS take your finger and poke them 3 or 4 times to see if you can get them to stay down.

Don't take anything as hard and fast rules... The density test should be used as a guideline only to steer you in the right direction, not as an elimination process.

If they give us liquids to use for identifying the plastics, they'll give us the densities of the liquids, right? And how would you tell the difference between high density polyethylene and low density polyethylene? The difference in density is only .025 g/cm. It says that the high density one is more translucent, but I couldn't find any pictures online of either of them.
Lastly, does sand give off a noticeable bad odor when iodine is added?

[computergeek3]

Lastly, does sand give off a noticeable bad odor when iodine is added?

It shouldn't...sand is a compound of silicon and oxygen (SiO2) so it should be extremely nonreactive. The only thing iodine is really good for is identifying cornstarch and Vitamin C.

[caseyotis]

Okay... It says on the wiki that ammonia has a "sweet" odor. However, in the kit that we got, it says that ammonia is NOT to be inhaled, and I accidentally did get a whiff of it and it smelled awful. My throat also did get a little bit irritated by it. Is this normal? At the competition, will we be able to open the beakers and sniff each liquid sample?