[samuelsmithmd]

I want to perform a demonstration (I used to have it from a kit, but lost it) and I can't remember what the reagents were...can anyone help?  The experiment was done safely by kids at room temperature and created a colorless solution that turned blue (though any color is fine) with the addition of a few drops of another colorless solution-  Then the blue color could be made to disappear with the addition of another few drops of another chemical-   anybody know what the chemicals may be and what would be the best way to go about purchasing them for demonstration? 

[Borek]

Sounds like some pH indicator.

Not exactly what you are looking for, but could be close enough - and interesting enough:

red cabbage experiment

[ARGOS++]

Dear Samuelsmithmd;

IMHO: This sounds more like “Methylene Blue”, a “RedOx-Indicator”, like “2,6-DCPIP” or “Diphenylamine”.
But the most ‘unperilous’ would be the “Methylene Blue”.
With a few drops of a mild “Oxidyser” and a  milde “Reducer” you can find in any household you are able to turn the color from Blue to colorless and visavers.

For  “Methylene Blue” you may read on:   "Methylene Blue”.


Good Luck!
                    ARGOS⁺⁺

[samuelsmithmd]

Both of these experiments Start with a blue solution-  the one I am looking for starts with a colorless solution and turns blue by adding a powder or colorless liquid-  and then can be reversed.    Any ideas?

[ARGOS++]

Dear Samuelsmithmd;

Could it be that you do an error in reasoning?

In both cases you are able to start at the “Indication State” you like.

For example:  If you add a few drop of  “Reducer” to the water before you add any “Methylene Blue”, so you will never see the blue color at the Begin.
Similar is true for “pH Indicators”!

Good Luck!
                    ARGOS⁺⁺