Forensics C

[Phenylethylamine]

NY forensics test required knowledge of Sherlock Holmes. I feel so stupid for never reading that...

Really? I did the NY Forensics test (got fifth, actually), and I somehow completely missed any reference to Sherlock Holmes... I mean, I guess I was holed up with the powders for two-thirds of the time, but still.

I was hoping for some cornstarch (because Oobleck) or ammonium chloride (because it makes such a pretty blue with Benedict's), but ah well. The potassium chloride was nice, that's always a pretty flame test.

[Steelfoam]

Does anyone have a good way to tell the difference between MgSO4 and Ca(NO3)2 besides the flame test. Does anyone from the wisconsin C -div state want to compare what they got on the powders?

[Dragonshark]

Does anyone have a good way to tell the difference between MgSO4 and Ca(NO3)2 besides the flame test. Does anyone from the wisconsin C -div state want to compare what they got on the powders?

I think there's a pH difference (MgSO4 is slightly acidic, while Ca(NO3)2 is neutral), but honestly, I'm not sure on this one, since I only use the flame test to tell them apart.
For the powders, I think I got 2 cornstarches, 2 magnesium sulfates, 1 ammonium chloride, and 1 glucose, though I don't remember the exact order. The first powder was cornstarch and the last one was glucose for sure, though.
Other things if you're interested: We said that Rosenbaum and Crittendon worked together to commit the crime, determining that from the evidence and also because the scenario said that they were known accomplices of each other. We identified the crime scene fiber as polyester, and the fiber found in one of their cars (I can't remember who) was also polyester. The unknown liquid was identified as kerosene from the gas chromatography, and the kerosene container had two fingerprints on it, which matched both of theirs. For the blood spatter question, we said that it hit at an angle of 30-45 degrees. I almost wrote on the case while trying to figure it out, but my partner fortunately stopped me; otherwise, we probably would have been DQ'd. (It was annoying that we couldn't write on the case at all; I wanted to take notes on it.) For the DNA question, I think we put down that it identifies Annie? (I don't remember her name, but the victim was female) Necessary as a victim only.

[Steelfoam]

I also got 1 glucose, and 2 cornstarch, at least one mgso4 but i think i got sucrose for one... i always get mgso4 and ca(no3)2 confused, we only got 6th.... no idea what my partner did at state.... we'll have to work wayy harder at nationals

[Phenylethylamine]

Does anyone have a good way to tell the difference between MgSO4 and Ca(NO3)2 besides the flame test.

Magnesium sulfate forms a white precipitate with NaOH (so dissolve some of the powder in water in your well plate, and put a couple drops of NaOH in there. If it's magnesium sulfate, you'll immediately see a pretty unmistakable white precipitate form; if it's calcium nitrate, nothing).

[Steelfoam]

Does anyone have a good way to tell the difference between MgSO4 and Ca(NO3)2 besides the flame test.

Magnesium sulfate forms a white precipitate with NaOH (so dissolve some of the powder in water in your well plate, and put a couple drops of NaOH in there. If it's magnesium sulfate, you'll immediately see a pretty unmistakable white precipitate form; if it's calcium nitrate, nothing).

Wait Calcium Nitrate DOESNT react with NaOH? I thought it did. Did you try it? because im pretty sure someone told me or i tried it at some point and it did react. Not sure though.

[BoldlyGoingNowhere]

What do we need to know about glass, other than shape, color, etc.? We have state next weekend and we want to know the specifics.

[Steelfoam]

What do we need to know about glass, other than shape, color, etc.? We have state next weekend and we want to know the specifics.

Know how to find the refraction also maybe fracture patterns? thats about it

[bloods]

NY forensics test required knowledge of Sherlock Holmes. I feel so stupid for never reading that...

Really? I did the NY Forensics test (got fifth, actually), and I somehow completely missed any reference to Sherlock Holmes... I mean, I guess I was holed up with the powders for two-thirds of the time, but still.

I was hoping for some cornstarch (because Oobleck) or ammonium chloride (because it makes such a pretty blue with Benedict's), but ah well. The potassium chloride was nice, that's always a pretty flame test.

Yeah, the way my partner and I divide it up is that he does powders and mass spec and I do everything else XD But yeah, there was a question asking what chemical process Sherlock Holmes used to identify fingerprints or something along those lines. With all the guessing, I'm surprised we almost made top ten!

[Phenylethylamine]

Does anyone have a good way to tell the difference between MgSO4 and Ca(NO3)2 besides the flame test.

Magnesium sulfate forms a white precipitate with NaOH (so dissolve some of the powder in water in your well plate, and put a couple drops of NaOH in there. If it's magnesium sulfate, you'll immediately see a pretty unmistakable white precipitate form; if it's calcium nitrate, nothing).

Wait Calcium Nitrate DOESNT react with NaOH? I thought it did. Did you try it? because im pretty sure someone told me or i tried it at some point and it did react. Not sure though.

Oh, calcium nitrate could react with sodium hydroxide – it just doesn't matter, because you would get sodium nitrate and calcium hydroxide, both of which are soluble in water and wouldn't precipitate.

In contrast, when you combine magnesium sulfate and sodium hydroxide, you get magnesium hydroxide (which is insoluble and forms the white precipitate you see) and sodium sulfate, so there's a visible white precipitate.