Hey chemistry experts - chem geek et al...

[no-mas]

When I took college inorganic chemistry, one of my instructors once did one of the coolest experiments - which he called a "freshman alarm clock" because it was silent, and would have no effect on one who is asleep....

Anyway, he added his solutions to a large beaker on a magnetic stirrer, and several seconds after adding the last one, the solution instantly turned from clear to black. Obviously it made an impression on me, as I remember the demonstration, but not what he was trying to teach

My question, however, is have any of you seen this and can it be duplicated by a home mad scientist? I've searched the net and youtube, but obviously can't remember the right terms to search....

 

[CaOCl2]

When I took college inorganic chemistry, one of my instructors once did one of the coolest experiments - which he called a "freshman alarm clock" because it was silent, and would have no effect on one who is asleep....

Anyway, he added his solutions to a large beaker on a magnetic stirrer, and several seconds after adding the last one, the solution instantly turned from clear to black. Obviously it made an impression on me, as I remember the demonstration, but not what he was trying to teach

My question, however, is have any of you seen this and can it be duplicated by a home mad scientist? I've searched the net and youtube, but obviously can't remember the right terms to search....

The Briggs-Rauscher Reaction here:
http://www.youtube.com/watch?v=NZ6Vr0ANGZg

"oscillating chemical reactions" is what you want to look for.

 

[no-mas]

I only remember it happening it once, instead of oscillating, but this must be it. Thanks so much!!

 

[AV8TOR]

Interesting find and I thought for a minute that I had found what I have been looking for too. I seem to remember an experiment that was very similar although it had one abrupt color change from clear to black in like 20 seconds after mixing. It went like having two pictures of clear liquid and then you start by pouring the complete contents of one into the other followed by pouring from one container to the other. If you time it right the color will change exactly while pouring. Anyone know that one? I believe a starch solution was in one container but I do not remember what was in the other.

 

[crabboy]

The guy holding the camera in the youtube video must have been nervous as heck. Waiting for it to explode perhaps.