Science Crime Busters B

[robotman]

You have to be able to test with the regents. How else would you be able to tell H2O and H2O2 apart.

If you shake them, the H2O2 (hydrogen peroxide) will make bubbles, water doesnt

I thought that after a period of time H202 will lose its ability to bubble when shaked

[fmtiger124]

I was always taught what Lake Superior said....but perhaps robot is right I wasn't in charge of liquids but I remember it never working too well

[icyfire]

Okay, so the iodine will not immediately react with the H2O2 but will bubble after around 30 seconds?

[Phenylethylamine]

Okay, so the iodine will not immediately react with the H2O2 but will bubble after around 30 seconds?

Thirty seconds, maybe longer. It depends on how old the hydrogen peroxide is. There have been times in competition when we've waited and waited, finally deciding all the samples must be water- and then like five minutes later, one of them starts bubbling. It's a delayed reaction, and the length of the delay can vary quite a lot.

[lakeSUPERIOR]

it's good to know both strategies, cuz both have their problem

depending on what type of container the liquid is given it it might be hard to shake/see the bubbles

[icyfire]

Okay, so the iodine will not immediately react with the H2O2 but will bubble after around 30 seconds?

Thirty seconds, maybe longer. It depends on how old the hydrogen peroxide is. There have been times in competition when we've waited and waited, finally deciding all the samples must be water- and then like five minutes later, one of them starts bubbling. It's a delayed reaction, and the length of the delay can vary quite a lot.

How much does it bubble? would it be enough bubbling to notice if we weren't paying too much attention to it? or is it tiny bubbles that you have to really look at to notice?

[robotman]

Okay, so the iodine will not immediately react with the H2O2 but will bubble after around 30 seconds?

Thirty seconds, maybe longer. It depends on how old the hydrogen peroxide is. There have been times in competition when we've waited and waited, finally deciding all the samples must be water- and then like five minutes later, one of them starts bubbling. It's a delayed reaction, and the length of the delay can vary quite a lot.

How much does it bubble? would it be enough bubbling to notice if we weren't paying too much attention to it? or is it tiny bubbles that you have to really look at to notice?

it pretty much coats the container in bubbles from what I have tested

[Phenylethylamine]

Okay, so the iodine will not immediately react with the H2O2 but will bubble after around 30 seconds?

Thirty seconds, maybe longer. It depends on how old the hydrogen peroxide is. There have been times in competition when we've waited and waited, finally deciding all the samples must be water- and then like five minutes later, one of them starts bubbling. It's a delayed reaction, and the length of the delay can vary quite a lot.

How much does it bubble? would it be enough bubbling to notice if we weren't paying too much attention to it? or is it tiny bubbles that you have to really look at to notice?

That varies too, but it's usually pretty noticeable. Certainly it was noticeable the few times we had super-delayed reactions like that; I saw it out of the corner of my eye when I wasn't even looking for it.

[melody2k6]

How can you tell what the mixed powders are?

[haven chuck]

Any thoughts on the Nationals test this year? I thought, above all, it was extremely well-run, and the giant stopwatch was a great idea.

[Phenylethylamine]

Any thoughts on the Nationals test this year? I thought, above all, it was extremely well-run, and the giant stopwatch was a great idea.

Was it run by the same guy as last year (tie-dye lab coat)? He was great, and I remember he used the giant stopwatch thing.

[haven chuck]

Yeah, it was that guy, and it was the best SCB event I've ever been to (and I've done it at States and Regionals the last 4 years).

[Phenylethylamine]

Yeah, it was that guy, and it was the best SCB event I've ever been to (and I've done it at States and Regionals the last 4 years).

Yeah, he was the NY State SCB supervisor last year (I'm guessing he was this year, too), and I was very happy to find he was the National supervisor too. He's the best SCB event writer anywhere. The fact that he's the National supervisor means that SCB is one of the few events that are guaranteed to be well written.

[haven chuck]

The only thing that shocked me was that there were no metals at all. Also, if anyone is curious, the water testing portion worked like this-
There was a sample of water and four data probes that hooked up to a TI-84 (not sure of the model) calculator. You just plugged the probe into the calculator, then placed it into the sample and it gave a reading. You needed to do 5 tests for full credit (and write down relevant conclusions about the liquid from each test).

[Phenylethylamine]

[quote="haven chuck"]The only thing that shocked me was that there were no metals at all. quote]
There were metals last year, I think, but he took out the polymers at the last minute (as in, they were in the materials given, and there was space on the answer sheet, but he told everyone not to use them).