I see that many people are posting asking for tips and good resources...so:
- I have my own personal powder chart and plastic flowchart that I'd be willing to share, PM me if you want that since I can't really upload it to a post. But for the most part, for plastics, I really just use density all the way since that's pretty much all you can do in competition. The national supervisor (THE WOZ) provides liquids that strategically have densities that fall in between the density values of the plastics themselves so they're easy to differentiate, and that's primarily what I used to make my flowchart. But not every competition has that supervisor, so I'm not sure how other competitions will run. Also keep in mind that PVC burns green and is the only of the eight to do so - while you can't actually perform this test in the lab (since I've heard burning these plastics can give off toxic fumes in addition to potentially disqualifying you from the event), some test supervisors may give you burn test information for plastics. This can save you time since you'll automatically figure out that it's PVC if the supervisor said that it burns green. For powders, the process of creating the flowchart was a little more taxing. I like the solubility test the best, the other reagent tests will work for specific groups of powders (i.e. HCl for carbonates), and the flame test should only be used if you suspect one of the chlorides (or boric acid, but that has a unique reaction with water that is easy to distinguish once you know what it looks like). Somehow we found that our conductivity meter lights up for everything including distilled water (but that has a dimmer light), so be sure to test that out on salt water and distilled water to make sure it works. But that does work for some powders.
- mass spec: http://ochem.jsd.claremont.edu/tutorial ... 3-min.html
- this is a 33-minute tutorial on mass specs. Be prepared to sit through it. I haven't done that yet actually
- For competition, I think the tips from samlan16, elephantower and boomvroomshroom are good - hands-on lab practice with the actual substances (in addition to finding out what they actually are) is key. I trained forensics competitors for my school by doing repeated drills of giving three random powders and asking them to identify them, and it worked wonders for me and my partner when we got to State. Then start keeping track of time once you know them since speed is incredibly important in forensics - aka strike a balance between slowing down to ensure good accuracy of identifications and to make sure nothing gets mixed up, contaminated or whatever but also between going quickly to complete all the identifications. Do this especially with your partner because most forensics tests are structured so that it's very difficult for one person to just carry all (imagine identifying every single powder and polymer, answering the test questions, and writing the crime analysis all by yourself - yeah not happening in 50 minutes unless you're just way too macho).
Well that's all I'll say for now.