|MadSci Network: Botany|
Many colors in plants are caused by anthocyanins, which change colors depending on pH. The vinegar "gas" will change the pH around the petals. Anthocyanins are often the red and blue colors found in flower petals. The greens and yellows are probably chlorophylls and carotenoids which are not sensitive, in the same way, to pH changes. There's lots of info on the net under "Anthocyanin" if you do a search. Good luck. David Hershey, Mad Science Adminitrator adds: A classic school exercise uses anthocyanins in red cabbage as a pH indicator: http://www.madsci.org/experiments/archive/859332497.Ch.html
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