Crime Busters B

[Skink]

You won't be pH testing metals. To test the powders, dissolve a small scoop in a small bit of water in one of your test tubes.

[theriddler]

Oh, sorry about that. I forgot how simple it was to identify metals.

[ajayd]

I'm still a little shaky about tin. Is tin yellowish or not? Because pictures are inconclusive.

[fantasyfan]

I am a crimebusters veteran and i noticed the only real difference in the rules this year was we have to analyse the composition of soil, and im not quite sure i understand what that means and haven't found any info on it anywhere. if you could explain what we should do that would be great

Thx for all of your help

[Skink]

I'm still a little shaky about tin. Is tin yellowish or not? Because pictures are inconclusive.

Pictures are inconclusive because color is not appropriate for distinguishing tin from metals like aluminum. Follow the flow chart.
*by the way...on the off chance it helps you (for an event like Metric Mastery, maybe), tin is much denser than aluminum.

[theriddler]

I'm still a little shaky about tin. Is tin yellowish or not? Because pictures are inconclusive.

Pictures are inconclusive because color is not appropriate for distinguishing tin from metals like aluminum. Follow the flow chart.
*by the way...on the off chance it helps you (for an event like Metric Mastery, maybe), tin is much denser than aluminum.

Can you post a link to the flow chart?

[aim4me26]

I'm still a little shaky about tin. Is tin yellowish or not? Because pictures are inconclusive.

Pictures are inconclusive because color is not appropriate for distinguishing tin from metals like aluminum. Follow the flow chart.
*by the way...on the off chance it helps you (for an event like Metric Mastery, maybe), tin is much denser than aluminum.

Can you post a link to the flow chart?

I don't know what flow chart Skink is talking about, but here's an excerpt from the Wiki that might help.

Almost every metal has a "give-away", making them fairly easy to identify-

Iron is the only magnetic metal
Copper is the only metal with a color other than grey (or similar).
Magnesium will often steam with HCl, and will also let off a strong odor when HCl is added.
Zinc will react vigorously (but will not steam) with HCl, and is non-magnetic.
Tin and aluminum are very similar (neither react very much with HCl), but there are a few things that can be done to tell them apart. First, tin often has a yellowish tint, which aluminum will never have. Next, tin is often fairly shiny, while aluminum is dull. Lastly, if the metal is very malleable, it is probably aluminum (think aluminum foil).

There's also a chart there that lists their properties, if you wanted to look at that.

[geekychic11]

Will pH paper be provided? Will HCl be provided? One common way to identify the substances is with its reaction to HCl. Or should I not use this tactic since it is time consuming?


I always brought ph paper in my kit. It's on the equipment list in the rules the HCl should be provided though... Using HCl to identify substances is the tactic that i always use. If you are worried about time then practice it with your partner and split up the list before the comp. EX- My partner always did mixed powders while I set up the chromatography, then I would do metals while she did plastics. This is a good way to manage the time you have in this event.

[Soccer_Girl]

pH paper will not be provided, although they do provide HCl. (I'm pretty sure that question was already asked, but whatever) I don't think HCl is very time consuming, but there are rarely reactions. It's up to you.

One thing that I've been having trouble with is the difference between salt and sugar. I've looked in the past year's forum, but they talked about it very vaguely. It doesn't really say anything on Google, either. Can someone help me with this? Thanks so much.

[Skink]

It's talked about vaguely for a reason: ID is kind of an art. Sugar and salt, for the purposes of this event, are the same except for their shape. Observe:

Salt


Sugar

or http://www.flickr.com/photos/22967304@N07/3429954619/ (can't link the picture)

According to the SO Crime Busters notes, salt should make 'uniform cubes' whereas sugar should be irregular. The difference is not as apparent with the first sugar picture as it is with the second. I'd suggest you go, grab a paper tower and a magnifier, and try it yourself.