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rooee wrote:Hey guys, newer member here. Just wanted to ask what sorts of powders would react with NaOH and if they do, if the dissolving process is slow or fast. Thanks!

NaOH reactions can typically be done two different ways: non-aqueous (i.e. putting drops of NaOH directly onto the powder) or aqueous (dissolving the powder first then dropping the NaOH in). When I did this event I could never get results for the non-aqueous but when doing Calcium Nitrate and Magnesium Sulfate with the aqueous, you will see a milky precipitate form as the product of the chemical reaction is non-soluble. The reaction is almost instantaneous. I find it not so great for IDing powders just because these two can be separated with a flame test but it might be helpful for you.

challis3 wrote:So this is my first year doing the event just wondering if anyone had tips for it i am currently working with my partner and have split up the work and have also done small amounts of work on each topic but not mastered a specific topic yet.

Splitting the work is honestly the best way to go about doing it, since most Forensics exams may be too long to finish without doing so. I would say one of the most important sections to get good at is Qualitative Analysis, since aside from the essay, it's the portion worth the most points. Polymers too, but that's something you could split with your partner (i.e. one study qual and the other study polymers). Chromatography could be done by either of you, depending on who thinks they can finish what they know how to do first. Same with the rest of the topics. When I competed, my partner and I also split essay and cleanup at the end, since penalties can be issued for improper cleanup.

All in all, just think strategically of how to split the topics with your partner, and focus on those.

Also, LAB PRACTICE. Seriously. It works wonders, esp since it helps you see what all the reactions and indicator tests are supposed to look like. There's also a roundtable on scioly.org/chat at 7 p.m. EST on Nov. 18, 2017, where myself and some other users who are experienced in lab events will talk about some of our tips for such! Feel free to join if you'd like to see what others have to say!

Magikarpmaster629 wrote:

rooee wrote:Hey guys, newer member here. Just wanted to ask what sorts of powders would react with NaOH and if they do, if the dissolving process is slow or fast. Thanks!

NaOH reactions can typically be done two different ways: non-aqueous (i.e. putting drops of NaOH directly onto the powder) or aqueous (dissolving the powder first then dropping the NaOH in). When I did this event I could never get results for the non-aqueous but when doing Calcium Nitrate and Magnesium Sulfate with the aqueous, you will see a milky precipitate form as the product of the chemical reaction is non-soluble. The reaction is almost instantaneous. I find it not so great for IDing powders just because these two can be separated with a flame test but it might be helpful for you.

Hmmm...usually I just remember using the flame test first and then using any of the other tests to confirm the identities.

For you lovely people who have taken an abundance of Forensics tests: Which of the part e topics are always matching between pictures/samples (never information recall)? I get the sense that pollen is like that, are there any others?

Panda Weasley wrote:For you lovely people who have taken an abundance of Forensics tests: Which of the part e topics are always matching between pictures/samples (never information recall)? I get the sense that pollen is like that, are there any others?

Bullet striations & Tracks/Soil (more tracks than soil though, I've only gotten one non-matching soil question).

sciduck wrote:

Panda Weasley wrote:For you lovely people who have taken an abundance of Forensics tests: Which of the part e topics are always matching between pictures/samples (never information recall)? I get the sense that pollen is like that, are there any others?

Bullet striations & Tracks/Soil (more tracks than soil though, I've only gotten one non-matching soil question).

Thanks!

Panda Weasley wrote:

sciduck wrote:

Panda Weasley wrote:For you lovely people who have taken an abundance of Forensics tests: Which of the part e topics are always matching between pictures/samples (never information recall)? I get the sense that pollen is like that, are there any others?

Bullet striations & Tracks/Soil (more tracks than soil though, I've only gotten one non-matching soil question).

Thanks!

Several other areas also have matching aspects besides having parts not based on matching that are tested on far more often, such as mass spec, DNA, and fingerprints.

Are multiple Appendices usually used because in the invitational I went they used many appendices and it can be slightly confusing sometimes.

depo1213 wrote:Are multiple Appendices usually used because in the invitational I went they used many appendices and it can be slightly confusing sometimes.

What do you mean by appendices?

pikachu4919 wrote:

depo1213 wrote:Are multiple Appendices usually used because in the invitational I went they used many appendices and it can be slightly confusing sometimes.

What do you mean by appendices?

I mean like where they refer to an apendix in a question and then you have to go into the back of the book to look for Appendix A or B.

For example the questions could be like determine the fibers. Fibers can be found in Appendix A. So you have to go to the back of the booklet for find it.

depo1213 wrote:

pikachu4919 wrote:

depo1213 wrote:Are multiple Appendices usually used because in the invitational I went they used many appendices and it can be slightly confusing sometimes.

What do you mean by appendices?

I mean like where they refer to an apendix in a question and then you have to go into the back of the book to look for Appendix A or B.

For example the questions could be like determine the fibers. Fibers can be found in Appendix A. So you have to go to the back of the booklet for find it.

Huh, I've never taken a test that has done that...