Science Crime Busters B

[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.

[geekychic13]

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.

how do you fit all of that on a piece of paper???
p.s. I have all that crap too, but I can only fit powders, SOME mixed powders, liquids, metals, fingerprints, hairs, fibers, plastics, (u don't need the DNA once you know how to match DNA) and I have the reactions in the powders, liquids, plastics, & metals, and a flow chart for plastic id. I have some blood spatter analysis, more plastic analysis, and pics for fibers and hairs

[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.

how do you fit all of that on a piece of paper???
p.s. I have all that crap too, but I can only fit powders, SOME mixed powders, liquids, metals, fingerprints, hairs, fibers, plastics, (u don't need the DNA once you know how to match DNA) and I have the reactions in the powders, liquids, plastics, & metals, and a flow chart for plastic id. I have some blood spatter analysis, more plastic analysis, and pics for fibers and hairs

Well, if you're wondering how I fit it all in, let's just say... I have my methods.... >.>

No, actually, the font is just pretty small, but still readable. I wouldn't say the font is super small, but it's fairly small. I've seen cheat sheets from other teams that have like... .5 font on them. I'm not lying. I swear.... the font is so tiny, I'm wondering how they can read it without a magnifying glass. However, next year, I might try to cram more stuff onto my sheet, since I (sadly) placed only 8th or something at States. *sigh*

[frogzorz]

in a mixture of baking soda and alka seltzer, how would tell that there is baking soda in the mixture?

sorry this is really late, but alka seltzer fizzes in both water and hcl and baking soda only fizzes in hcl.

[prelude to death]

in a mixture of baking soda and alka seltzer, how would tell that there is baking soda in the mixture?

sorry this is really late, but alka seltzer fizzes in both water and hcl and baking soda only fizzes in hcl.

But then, how would you know that the mixture has baking soda in it? Like, if you have a mixture of 2 in front of you, and you test it in the HCl, it fizzes. Then, you test it with water, and it fizzes. So you know that the mixture has alka seltzer in it, right? But how would you know if it has baking soda in it? (Because the mixture fizzed with HCl and water.) Would you then look under like, a magnifying lens or something to separate the powders apart by shape and then individually test each one? Or is there another way?

[poparteeb2]

@ prelude to death: alka seltzer is more powdery than baking soda :]. you should be able to tell if there's alka seltzer in it by using a magnifying glass. also, USUALLY, the mixture won't be very evenly mixed, meaning that in some sections the water won't affect the powder at all but the hcl will, and in other sections both water and hcl will affect the powder. also, there are different types of fizzing: I haven't practiced for a while, so I forgot which is which, but I believe alka seltzer is more of a "quick fizz", while baking soda creates this huge bubble. or, it may be the other way around...