Science Crime Busters B

[geekychic13]

To what extent do you have to study for the mixed solids crystal analysis segment of the state test?
P.S. prelude to death, you totally stole my avatar

In the rules manual, it says that at Regionals, you will get up to 2 mixtures of 2 solids. At States, you'll get around 2 - 4 mixtures of 2 or 3 solids. At Nationals, you'll get 2 - 6 mixtures of 2 or 3 solids. So I'd advise you to start studying for your Regionals test (if you had it already) with 2 solids in a mixture, and once you feel that you've mastered 2 solids, start timing yourself to see how fast you and your partner can identify them. Then, move on to 3 solids in a mixture until you're super sure you've mastered them. I know that I'm really bad at mixtures and I take forever at them, but my partner is really good at them and can tell a lot of stuff just by looking at the mixture, even without a microscope!

P. S. I believe you stole my avatar, geekychic13. As you can obviously see, I joined first, and I remember that I added my avatar around a week or so upon my date of joining.

thanks, oh and my state's 2 weeks away so thanks a villion million (which is too a word that I made up, but it;s a word)
P.S. psshhhhh, that's besides the point

[arugi]

This is probably going to be one of the latest posts before a competition. PLEASE try to answer quickly, as the SUNY-Ulster NY States is tomorrow.

What do you put on a reference sheet? I have powders, liquids, metals, plastics, fingerprints, blood projection, spatters, hairs, fibres. Is there anything else worth adding? I have half a page remaining. Thank you and goodbye.

[prelude to death]

Yeah... I have powders, liquids, metals, fingerprints, hairs, fibers, plastics, and DNA chromatograms or whatever. Also, I have a whole reaction table for powders and metals, as well as flow charts for easy identification for metals and powders. I especially like my flow chart for powders. If you want to take a look at it, I think it should be in soinc.org under event "Crime Busters" as a reference.

[icyfire]

Can salt, sugar, and sodium acetate crystals be crushed into poweders for unknowns?

[prelude to death]

There was a discussion about this on the 5th page or so involving salt and sugar being grinded up, but not sodium acetate. However, it seemed unanimous that no one had ever seen salt and sugar being grinded up before. With sodium acetate, I would infer that it would the the same, since sodium acetate has pretty much no reactions. With salt and sugar, the only real way (besides a taste test) would be to look at it visually (with or without a microscope.... both are fine). Know, however, that sodium acetate is a base, meaning that if there are no reactions with HCl and the unknown is a base, then it is most likely sodium acetate, seeing as baking soda fizzes with HCl.

[dholdgreve]

So... How can you logically deduce a mixture of Baking Soda and Calcium Sulfate (gypsum)... From Baking Soda and Calcium Carbonate? Doesn't the baking soda mask the effervescance of the CaCO3? Since the switched from Plaster of Paris to Gypsum, it know longer sets up, so how do you tell?

[poparteeb2]

Well Calcium Carbonate looks different from Baking Soda, so that's how you would tell . Just practice a lot!

to anyone at the new york states (anyone else could read too): All the metals I was given had delayed fizzing after a while, and had a bright silvery sheen...that would be aluminum, correct? (but I've heard tin also reacts with HCL delayed). also, was there any zinc? because zinc usually reacts straight away, and is pretty dull....

thanks in advance!

[Efficiency]

to anyone at the new york states (anyone else could read too): All the metals I was given had delayed fizzing after a while, and had a bright silvery sheen...that would be aluminum, correct? (but I've heard tin also reacts with HCL delayed). also, was there any zinc? because zinc usually reacts straight away, and is pretty dull....

..I got Aluminum for just about every single one of them, but I think I was paranoid and thought that I was probably getting a lot wrong, so I threw in tin for one of the answers as well, since I think one or two had barely a slight yellowish tint. But as I recall, I believe they all had a bright silvery sheen like you said.
As far as I know, I didn't get any zinc. And yeah, I believe tin has a delayed HCl reaction, but I'm not completely sure.

[poparteeb2]

^I know you efficiency.

But aluminum has to have that little layer stripped off to react, right? so i suppose that's why it's delayed...

On the other hand it's pretty obvious if you have an "aluminum" sample to see if there's tin or not. At our school we only have very yellowish tin. Do any schools have tin that's only a little bit?

[Efficiency]

^I know you too
Oh, haha, I never learned that about aluminum. But I guess it's true, it sound perfectly legitimate to me.

Argh, okay. Because I also heard that tin can also have slight yellowish tint, and I always thought that the yellowish tint could vary, but I guess it's totally possible that I'm wrong. I just never tested with metals before aside from the competitions, just had the reactions memorized, haha. ..But yeah, I think you're right.