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Hello. I'm a newbie and I have NO IDEA what I'm doing. Please give me any tips!!!

Incineroar999 wrote:Hello. I'm a newbie and I have NO IDEA what I'm doing. Please give me any tips!!!

Practice, practice, practice! Speed and accuracy is your goal! Practice identifying powers a lot. Get the powders, some test tubes, and ask a team mate to pour some of the powders into different test tubes. Make sure they remember what is in which test tube and that you don't see what they're doing. Try and identify the powers and see how you do. Also, a great resource page can make or break you. Make sure you have good diagrams to id powders, liquids, and metals. Make sure you also know how to id types of hair and fingerprints. Another important thing to get good at is matching footprints and tire tracks. Good luck!

Incineroar999 wrote:Hello. I'm a newbie and I have NO IDEA what I'm doing. Please give me any tips!!!

Save plenty of time for the analysis (at least 20 minutes).

I attended the Bayard Rustin invy on 01/05, and the proctors for CB included two crushed up metals as two powders. Is this allowed?

Rivkaaa wrote:I attended the Bayard Rustin invy on 01/05, and the proctors for CB included two crushed up metals as two powders. Is this allowed?

No, the rules state,"Qualitative Analysis: Participants will identify evidence (unknowns) by performing tests such as solubility, acidity, magnetic property, color, density, and odor. Every team will have the same set of unknowns (evidence). The scenario will identify which containers hold mixtures and if the mixtures are made of two or three materials. The unknown common materials will be taken from the following lists.

i. Solids: Anhydrous sodium acetate, yeast, vitamin C (ascorbic acid), *calcium carbonate (powdered limestone), *table salt (NaCl), *sugar (crystal), *flour, *calcium sulfate 2H2O (gypsum), *cornstarch, *baking soda, *powdered gelatin, *powdered Alka-Seltzer®, *sand (white).

ii. Non-Powdered Metals: aluminum, iron, zinc, magnesium, copper, tin.

iii. Liquids: lemon juice, rubbing alcohol (isopropyl), household ammonia (3%), water, vinegar,
hydrogen peroxide (3%).

If the metals were powdered that would not follow the rules.

Incineroar999 wrote:Hello. I'm a newbie and I have NO IDEA what I'm doing. Please give me any tips!!!

Study powders, metals, and liquids like crazy!! They are so so important. Make sure you know the difference between different kinds of fingerprints and ONLY PUT WHAT YOU NEED ON YOUR CHEAT SHEET. Also make sure you leave time for your analysis (I suggest using bullet points), which should be written by whoever is done first. Underline useful information (what animals the suspect has, what kind of clothes they wear, etc.) and learn at least a bit about the history of forensics (like the father of fingerprinting, wha CODIS stands for, what IAFIS stands for, etc.). Learn about DNA and its 4 nitrogenous bases, know what DNA stands for, and basically just know about DNA. Just.... make sure you know the 4 nitrogenous bases and the biggest differences between unknowns like the back of your hand and edit your cheat sheet as you go. And please please always remember the analysis, it is so many points and is important okay.

I hope this was able to help!! I know it was a lot, but there is a lot to know!!!

scipanther55 wrote:Hey Guys,

Wondering if we are allowed to conduct a scratch test for metals?

Also,
Does anyone know what liquids they will provide when testing the density of plastics?

Thanks

I have never conducted a scratch test, I look at the color, see if it is magnetic, and see how it reacts with HCl.

I actually looked up what liquids they will likely be using!! Corn oil, 70% isopropyl alcohol, 10% NaCal solution, 25% NaCl solution, saturated NaCl, and water. This may not be completely correct, but it is what I had written down and I am pretty sure it is what will be used.

Last year at states I tried using it for a sample that I was 99.999% sure was flour, but it wouldn't react. Also, I accidentally got it on a wool(?) sample and it turned brown. Can someone explain this?

At this one competition, they gave vinegar as an additional reagent to HCl and iodine, what is the purpose of vinegar in IDing unknowns?

amk578 wrote:At this one competition, they gave vinegar as an additional reagent to HCl and iodine, what is the purpose of vinegar in IDing unknowns?

The only thing I can think of is with baking soda