Looking for a "Mr. Wizard" chemistry demonstration

[Cavermike]

Hello again, you guys and gals have been a wealth of knowledge during my membership but I am looking for some help.

I am wanting to do a demonstration in my classroom that I once saw on the show Mr. Wizard. The experiment consisted of starting with 2 clear liquids in seperate beakers. A young student would then, mix the beakers, back and forth, repeatedly. Then all of a sudden the clear liquid would turn dark blue instantly. It took about 10 seconds of mixing for the change to occur. Any ideas as to what chemicals they were mixing?

Thanks in advance.

[cope]

Here is a similar demonstration that a chemistry prof at the University of Illinois used to do for a general audience just before Christmas break every year (U of I also has orange and blue as its team colors).

Clear added to clear creates orange and clear added to that creates dark blue. The prof used to sing the alma mater song (and entice the enthusiastic audience to sing with him) as he mixed the solutions..."Hail to the orange" (add clear solution to clear solution)...(wait)...(turns orange)...(add second clear solution to orange solution)..."Hail to the blue"...(turns dark blue).

It is not exactly what you are looking for but it looks doable as a school demo.

Link

[trinitree88]

Hello again, you guys and gals have been a wealth of knowledge during my membership but I am looking for some help.

I am wanting to do a demonstration in my classroom that I once saw on the show Mr. Wizard. The experiment consisted of starting with 2 clear liquids in seperate beakers. A young student would then, mix the beakers, back and forth, repeatedly. Then all of a sudden the clear liquid would turn dark blue instantly. It took about 10 seconds of mixing for the change to occur. Any ideas as to what chemicals they were mixing?

Thanks in advance.

Cavermike. OTOMH...That would be the "clock" reaction. Solution A is 10 grams of Potassium Iodate in a liter of water. Solution B is a little trickier. First boil a liter of water. Then add a cold water dispersion of soluble starch...you can use supermarket corn starch in a pinch, but the result will be hazy. Use about 1 gram of starch in 10 ml of COLD water for the dispersion. This is essential to avoid clumping. When adding the starch dispersion to the hot water, trickle it in and use vigorous stirring. In about two minutes it will hydrate, making the liquid light blue. Technically it's a colloidal dispersion, not a true solution. Let it COOL to room temperature. Then add, with gentle stirring ~ 1 gram of Sodium Metabisulfite. (This is from memory...you might have to adjust concentrations).
When mixed the iodate is reduced to elemental iodine by the bisulfite. The starch then forms the starch-iodine complex...deep blue. A single drop of sulfuric acid is sometimes used to promote the reaction. Mix equal volumes of solutionA and solution B in a test tube or beaker and time it with a stopwatch. You can dilute to slow the reaction down, or add KIO₃, and bisulfite to increase conc. and speed things up. Fun. Pete.

There's a slightly different two-step reaction called the Old Nassau...goes orange/yellow....then black.

[Cavermike]

Here is a similar demonstration that a chemistry prof at the University of Illinois used to do for a general audience just before Christmas break every year (U of I also has orange and blue as its team colors).

Link

LOL, this is pretty funny because I teach in Illinois. I think my students would get a kick out of this because I'm from Indiana.

Cavermike. OTOMH...That would be the "clock" reaction.

This sounds very familiar. Thank you.

[BigDon]

Another good one I remember from high school chemistry, though a little messy, is get a straight sided beaker about three to four inchs in diameter, put in about an inch or two of white sugar then pour on some sulferic acid. Rapidly pour on alternating layers of sugar and acid then back away. (Eye protection and a face shield are recommended)

When the reaction kicks in you get a column of carbon suddenly thrust up out of the beaker that's like one of those "snakes" you light up on the Fourth of July. While its happening it looks for all the world like you just made a Shoggoth in your classroom. Like all good recipes you might want to practice it once or twice before doing it in front of guests.

[BigDon]

Oh, and only fill it half way! The sides act as a guide then.