Science Fair Project - Topic - What color will be absorbed fastest by celery. I have been assuming that the color with the smallest molecule would be absorbed fastest but I can't find any reference material on the size of color molecules. Any ideas how to research.

Answer 1

Isn't dye movement caused by osmosis? Isn't osmosis dependent on osmotic pressure, which is solely dependent on concentration, not solute size?

http://en.wikipedia.org/wiki/Osmosis

So this prediction is that you are wrong. However, I would continue with your investigation, sometime known facts are wrong. I am wondering how you will verify all your dyes are at the same concentration.

Answer 2

When you say 'absorbed by celery' do you mean transported with the water transport in the stem to give the colour in the leaves? Xylem vessels are visible under an optical microscope so must have a diameter that is hundreds of molecules wide. Perhaps worth researching the diameter?

As for the size of the colour molecules the easiest way to do this is to make a molecular model and measure it! Also for a science fair the models have a strong visual impact so you could demonstrate the size difference.

For example Amaranth (a red dye) the molecular structure is on wikipedia

http://en.wikipedia.org/wiki/Red_dye_number_2