Just got back from my first full experience of Forensics at competition... and I failed! I was not expecting a full on crime scenario to take up the entire event. I was moreso expecting half exam and half scenario, I guess I was wrong.
I was under pressure the entire time and having 10 bunsen burners on in the room didn't help with the sweating haha. Anyways, it's in the past now so oh well. I had a few issues with solubility. What should be the deciding factor for solubility? I feel like my powder analysis was completely thrown off by me thinking a powder is soluble when it's actually not and vice versa. I saw some solutions where the powder seemed kind of "suspended" in the liquid and others where i thought the powder was soluble but none of my further tests worked. What are your guys' go-to solutions for solubility?
Heh, time is probably the biggest challenge with this event... Just try a lot of practice tests and make sure you can get through the qual fast.
As far as solubility, I think the best advice is to try all the powders by yourself, come up with a really consistent method to test it, and then write down all your own results as you can describe them. It's a lot better than going off of internet descriptions.
For solubility, if it settles, it's doesn't dissolve. But to tell quick, if it makes a cloudy mixture, it's undissolvable. If the mixture is clear with some grains, or floating bits, it's dissolvable.
Try to go off of many sources to learn and get a generalized idea of what each powder will do, and definitely write it down. It won't be easy to memorize it all on the first try. If there are any people who did Forensics last year in your team, try to get in contact with them and get them to tell you all that they can tell you. That's how i learned, I went off of their info and tested all the powders side by side, comparing all of them lined up. Did multiple test on the same powder to find consistencies, inconsistencies, and distinct features. To get faster, what I did was get someone to set up 8 powders (or 10, or 12, the max per competitions) and time myself.(I sent 15mins for 8 at first) Memorized the distinctive features of the powders, I mostly rely on burn tests, almost all the powders burn differently. A few can be similar, but there's always something. If there isn't, then I just use process of elimination, and pH test to confirm it. Practice is the key to speed!(and memorization)
After doing so many practice test, I went from doing 8 powders in 50 mins(1st try, too long!!) getting 7/8, 8 in 20mins(2nd)6/8, then i forgot a lot, but with all the powders I got wrong I retested them. Now i can do 8 powders in 8 mins :} with 7/8 right, or around that time, 7-9 mins.