Science Crime Busters B

[geekychic13]

A strategy I use for seeing if baking soda is with alka seltzer is separating them a bit, then drop water into what I think is the alka seltzer, and then dropping water into what I think is the baking soda.

Anyways, for some reason I'm having a lot of trouble with the metals. First--I simply cannot tell the difference between aluminum and tin. Because the samples are so small, I can't tell which one's heavier. No one reacts. I can't tell if it's "yellowish" or not without another frame of reference. How do you guys figure it out?

Also, will they give you different "forms" of the metals? So far I've gotten aluminum foil, aluminum lumps (like little balls of aluminum), tin foil, dull lumps of zinc, zinc filings, iron filings, magnesium pellets, copper strips, and copper lumps. Are there any other "forms" (like balls, strips, etc.) of the metals, because the different forms really look different....?

Same here. The dull lumps of zinc you got are probably mossy zinc (molten zinc dropped into water), which looks absolutely nothing like normal zinc.
Obviously, iron is magnetic (it also rusts after contact with water), and copper is copper. Tin foil actually does have a yellowish sheen, but it can be quite variable. The tin foil that I got was dull but rather reflective, and the "yellowness" of it was fairly obvious when compared with other metals. Just compare it with your tweezers/metal scoops/test tube rack/etc., and if you don't have any of those, just bring a paper clip or something. Aluminum tends to be brighter and more silvery, and when I tested it, it also didn't react with HCl.

Actually, that way of identifying mixtures is not 100% accurate, because there will still be some of each in the two "separated" powders, so the best way to actually identify they mixture's components is to test the reactions beforehand and put most of the results in your notes. Anyway, you would have had to have had the results for individual solid crystal analysis in your notes to do your idea. But a good alternative to when you can't or are underprepared for a competition.

[arugi]

I don't understand what we should know for spatters at the competition. Could someone please give me some info on that?

[prelude to death]

To the extent of my knowledge and the competitions I've been to, they give you pictures of blood stains or other liquid (like juice) that has been dropped/spattered on the floor, and you have to label it with what you think caused it (like a gunshot or a soda can that was thrown across the room). Additionally, in some competitions, they might give you choices that include to speed of the spatter and you have to correctly match it up.

[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

[prelude to death]

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.

[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.