Science Buddies: "Ask an Expert"

I am doing a project on how different waters affect the absorbtion by the plant. I colored well water, bottled water and tonic water. I placed celery stalks in all three waters. The celery in the tonic water did not turn color. I think this is due to the quinine in the tonic, but I don't know why the color does not get abosbed. Any help is appreciated.

Hi there. Tonic water is different from your other kinds of water in several ways, as it is carbonated (has dissolved CO2), contains quinine, contains sugar, and also probably has a preservative like Sodium Benzoate. What brand did you use and what ingredients are listed on the bottle? To determine which of these is responsible for the effect you would need to add those ingredients to purified water 1 at a time. You can get close to an answer by testing sugar water and seltzer water (dissolved CO2 only) in addition to the things you have already tested. Quinine and sodium benzoate will be more difficult to come by, though.

Cheers,
Colin