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dnzsnr wrote:Anyone have a link to a good dichotomous key to use for powders?

I use a chart, not sure if there are any physical dichotomous keys but the intellectual bois probably have the sequence of testing memorized. I suggest that you start with a flame test and go from there.

jimmy-bond wrote:

dnzsnr wrote:Anyone have a link to a good dichotomous key to use for powders?

I use a chart, not sure if there are any physical dichotomous keys but the intellectual bois probably have the sequence of testing memorized. I suggest that you start with a flame test and go from there.

Yeah the flame test is very helpful and can single out a large number of the powders. It also can help to consider what each of the powders look like and quickly narrow it down before doing some tests.

Do polar or non polar substances travel farther in chromatography (using water as solvent)?

dnzsnr wrote:Do polar or non polar substances travel farther in chromatography (using water as solvent)?

I believe polar substances would travel further because they would attract to the water molecules

Edit: I'm actually not sure about this since I believe in paper chromatography the paper is polar as well

What are some common mass spectra that come up on tests? I've noticed hexane and caffeine are both relatively common, and I was wondering if there were others.

Has anyone here gone to nationals and done forensics multiple times?

wec01 wrote:Has anyone here gone to nationals and done forensics multiple times?

I haven’t been to nationals multiple times (only once) but I’ve done forensics with the national supervisor breathing down my neck several more times at all the other levels of competition (which incidentally did prove to really help with facing her again at nationals itself)...need advice?

pikachu4919 wrote:
I haven’t been to nationals multiple times (only once) but I’ve done forensics with the national supervisor breathing down my neck several more times at all the other levels of competition (which incidentally did prove to really help with facing her again at nationals itself)...need advice?

lol, *Hammond invy and IN State* and her tests are reallyyyyy different from any others I took. It's just something about them that makes them harder. The way they're set up makes it difficult to keep things straight, as we can't mark suspect sheets. Idk, they're just different and harder. Also, she doesn't explicitly state which unknowns are mixtures, which is annoying. It said all powders found on the suspects are suspected to be mixtures, but no mix. of 2 or 3, gotta figure it out.

CPScienceDude wrote:

pikachu4919 wrote:
I haven’t been to nationals multiple times (only once) but I’ve done forensics with the national supervisor breathing down my neck several more times at all the other levels of competition (which incidentally did prove to really help with facing her again at nationals itself)...need advice?

lol, *Hammond invy and IN State* and her tests are reallyyyyy different from any others I took. It's just something about them that makes them harder. The way they're set up makes it difficult to keep things straight, as we can't mark suspect sheets. Idk, they're just different and harder. Also, she doesn't explicitly state which unknowns are mixtures, which is annoying. It said all powders found on the suspects are suspected to be mixtures, but no mix. of 2 or 3, gotta figure it out.

The hardest thing about them is the length - it's always absurd in the wrong way. Like it'll be loaded with maybe 50+ easy trivia, and it just becomes a race of who can finish the most without screwing up. I really don't like it, but she doesn't change much at all, so it is what it is.

pikachu4919 wrote:

CPScienceDude wrote:

pikachu4919 wrote:
I haven’t been to nationals multiple times (only once) but I’ve done forensics with the national supervisor breathing down my neck several more times at all the other levels of competition (which incidentally did prove to really help with facing her again at nationals itself)...need advice?

lol, *Hammond invy and IN State* and her tests are reallyyyyy different from any others I took. It's just something about them that makes them harder. The way they're set up makes it difficult to keep things straight, as we can't mark suspect sheets. Idk, they're just different and harder. Also, she doesn't explicitly state which unknowns are mixtures, which is annoying. It said all powders found on the suspects are suspected to be mixtures, but no mix. of 2 or 3, gotta figure it out.

The hardest thing about them is the length - it's always absurd in the wrong way. Like it'll be loaded with maybe 50+ easy trivia, and it just becomes a race of who can finish the most without screwing up. I really don't like it, but she doesn't change much at all, so it is what it is.

Yeah, I remembered the nats test last year being like that and was hoping maybe it was a fluke, but looks like it wasn't.