Is There A Chemical.....

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Is there a chemical that is non-toxic, clear, and goes from clear to a color when it comes into contact with oxygen or carbon dioxide? kind of like how blood turns red when it comes into contact with oxygen.

[UncleAl]

Leucomethylene blue - colorless when reduced to deep blue when oxidized, and reversible. Classic demo is a trace of methylene blue plus glucose in water, shaken in a jar with air.

Basic phenolpthalein will reversibly decolorize with CO2, but it will be slow.

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i was thinking maybe a chemical that is cheap to produce, like for use in a sales product. I read up on Leucomethylene blue and it is used to lower the levels of methaemoglobin in red blood cells, sounds kinda expensive.