Crimebusters?

[haven chuck]

No, it wont. He's saying that since it is insoluble, the HCl will not be able to reach it since it will be at the bottem and i guess HCl is less dense then water. The baking soda, which is fairly soluble, will be mixed in and the parts that are on top (with the water) will be open for the HCl to get to. At least this is my interpretation of that but i've never tried it so i dont know for sure

[Phenylethylamine]

I found that it worked if the two were mixed, that if you add water first and let the fizz from the calcium carbonate settle, then you could add vinegar, if it was a really big reaction then there's baking soda. If not (a small reaction)then its just calcium carbonate

I was referring to this post, not the one by dholdgreve. I meant that if you add water first, there shouldn't be any fizz from the calcium carbonate to let settle.

[zoproeg]

A good chromatogram:

Draw a pencil line at the bottom of the paper. In div. B they usually have the pen from the crime scene on the paper, so you would obviously draw the lie through that dot. then, draw dots w/ each of the other pens on the dot, trying to make them as small and concentrated as possible. LABEL IN PENCIL!!!! DO NOT FORGET WHICH DOT IS WHICH!!!!!
Now, you either hang the paper into the beaker off of a pencil or something, or you can fold the paper in half (slightly) and stand it up in the beaker. Add water so that none of the dots are submerged and no water is splashed onto the paper. Good luck!!

[haven chuck]

I found that it worked if the two were mixed, that if you add water first and let the fizz from the calcium carbonate settle, then you could add vinegar, if it was a really big reaction then there's baking soda. If not (a small reaction)then its just calcium carbonate

I was referring to this post, not the one by dholdgreve. I meant that if you add water first, there shouldn't be any fizz from the calcium carbonate to let settle.

Oh, im sorry, i must've misread your post.

[RaiderRed1026]

I thought you were talking about alka seltzer
srry, no it should not if its calcium carbonate

[carlswife]

hi, this is my first year coaching and i am getting absolutely no help at school as far as this

can anyone help me with the mixing of the chemicals, (baking soda, salt, etc. mixing with water, iodide and vinegar)

what do i use to put the mix in and how much powder with how much liquid ?

do i actually mix it with like a toothpick? then after it is mixed, what am i wanting the kids to do with it? like what do they need to know about it?

sorry, but i am LOST, i want to make sure i teach them right but i dont know what is right

thanks for any help, you can email me privately if you want at [email protected]

thanks
Michelle

[dudeincolorado]

To mix chemicals I would use a chem tray something like this


here's the link http://www.stevespanglerscience.com/product/1395
but if you can not get this the styrofoam bowls with the flat bottoms will do. (Just make sure the HCl doesn't melt the bowl!)

To mix powders and the chemicals put just a little bit of powder (like the tip of a teaspoon) in one of the wells or on one side of the bowl and then add a drop (from a dropper) to the powder. Do this for all Water, HCl, and Iodine.

If you're using the well trays use one column per powder and one row per chemical. You should be able to easily compare reactions this way.
If you're using the bowls put the powders on opposite sides of the bowl. (You don't want them to mix). You can compare reactions by putting the bowls together. (Just make sure you mark which section of the bowl has which chemical!)

You don't actually have to mix the chemicals; most reactions are instant.

Here's what you are looking for for each chemical.
Water: solubility, pH
HCl: fizzing
Iodine: blackening of the powder, clearing the Iodine (the regular reaction is just a brownish color)
On top of that you are looking for fizzing of the powder to EVERY liquid not just HCl, gelling of the powder, and hardening of the powder.

Each one of the chemicals should have a specific combination of these reactions.

Have the people your coaching fill out this chart while they are testing the chemicals http://soinc.org/sites/default/files/up ... ksheet.pdf
and to check you reactions check the wiki here http://scioly.org/wiki/Science_Crime_Busters

You might find this site helpful if you haven't found it http://soinc.org/science_crime_busters_notes

Good luck and I hope you find this event as fun as I do

[RaiderRed1026]

my coach takes ketchup cups, puts maybe a half a 1/4 teaspoon of each powder and uses the stick part of a spoon to stir it. we just use little squares of paper to do our tests on

[paradoxgirl]

squares of paper? really? huh. i never thought something like that would work. i always use chemical mixing trays, like that picture up there. just not as colorful

[dholdgreve]

For what it's worth, I've run a bunch of Crime Busters and Forensic Competitions at various invitationals over the years, and many times they are scheduled for first and second periods (I'm not sure why though). The few times they have been run later in the day, there is usually an event being run in that room the period immediately before... In any case, there is rarely enough time to create all of the evidence samples the morning of the event, so I've been going to my local Wal-Mart and buying the 200 count boxes of 1-1/2"x 2" zip lock bags used for bead collections. A box costs about $3, so the cost per bag is less than 2 cents, making them economically disposable (although not the greenest solution). I also tapped our local County Forensic Lab for a donation of 50 large brown Evidence Envelopes that we have reused now for three years. This helps give the event a small dose of realism. In each of the zip locks, I place a small paper number generated from an excel matrix and used to identify which evidence they are looking at. This seems to really work well, and allows the Event Proctor time to prep as much as a week ahead of time. One of our local Hospitals did some house cleaning a few years ago and threw out several hundred 10 ml plastic vials with screw on caps. We snagged them as well and recycle those from competition to competition to hold the crimebusters liquids.