Science Crime Busters B

[EpicFailure]

For the past Regional and State Competition, we've had to ID strands of hair in plastic bags with no microscopes. Is this just a faulty set-up or is there a way we can ID dog, cat, human hair just by looking at it (or with a hand lens)?

By any chance did your test have to do with a dog being abducted?

My parter and i had to just rely on the length and color. We ended up placing 5th though.

I don't remember the test a lot but I don't think so as it was a WI State test. What is a good way to distinguish between types of fibers with a compound microscope (when given only one strand of each fiber)? When we tried it, the only thing we could tell was the weave pattern.

[geminicross]

For the past Regional and State Competition, we've had to ID strands of hair in plastic bags with no microscopes. Is this just a faulty set-up or is there a way we can ID dog, cat, human hair just by looking at it (or with a hand lens)?

By any chance did your test have to do with a dog being abducted?

My parter and i had to just rely on the length and color. We ended up placing 5th though.

I don't remember the test a lot but I don't think so as it was a WI State test. What is a good way to distinguish between types of fibers with a compound microscope (when given only one strand of each fiber)? When we tried it, the only thing we could tell was the weave pattern.

I honestly think that's the best thing to go on. (Of course there are tons of people on this site with more experience than me.)

[Cheese_Muffin_Man]

can someone tell me the difference between zinc and aluminum?

[Skink]

can someone tell me the difference between zinc and aluminum?

17 protons.

The flow chart and tables say that one will react quickly with HCl while the other is delayed. I can't tell you wha that looks like in practice because I don't have these samples, but I'd try it at least once if you can.

[Cheese_Muffin_Man]

can someone tell me the difference between zinc and aluminum?

17 protons.

The flow chart and tables say that one will react quickly with HCl while the other is delayed. I can't tell you wha that looks like in practice because I don't have these samples, but I'd try it at least once if you can.

thanks!

[SciBomb97]

can someone tell me the difference between zinc and aluminum?

17 protons.

The flow chart and tables say that one will react quickly with HCl while the other is delayed. I can't tell you wha that looks like in practice because I don't have these samples, but I'd try it at least once if you can.

thanks!

Yeah, we tried this one so many times at practice (the 6th graders...they never get used to it).
For aluminum, there is definitely a delay between contact and reaction. You have to wait like a whole minute to about 2 minutes before something happens. When it does start to react, there will be a slight fizz followed up by a pretty violent bubbling that lasts for about 10-20 seconds.
Zinc, on the other hand, will react upon contact with HCl by fizzing at a realtively constant magnitude. It won't be anything very violent, just some moderate fizzing.
Also, there may be some confusion between magnesium and zinc. While zinc has a moderate fizz on contact, magnesium will practically evaporate on contact and bubble violently if a piece is dropped into a fair amount of HCl. You'll see what I mean if you ever get to try it.
Hope that helps.

[Cheese_Muffin_Man]

Thanks! i think it will help us out a lot

[Cheese_Muffin_Man]

how can u test for gypsum?

[Skink]

The best approach is NOT to rule out things (ie "Test for Gypsum"/"Test for Calcium Carbonate") unless you already have a good guess as to what something is, but the best approach is to simply follow the flow chart, which is page 2 of that link. If you have a hunch you know what it is, you can skip steps.

[EpicFailure]

Has anyone tested Ascorbic Acid and got a pH other than 2? Same with Alka-Seltzer. Has anyone gotten a pH other than 6 for that?