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Color separation

Postby abhishekraut » Tue Jan 19, 2016 8:59 am


I am parent of 3 year old and this question may not be for that age. So moderators are requested to move this science question to appropriate section.

I usually show simple science experiments to my 3 year old son to have him develop interest and most importantly have fun. Last time, our simple experiment was as easy how to float an egg by adding salt in water. In doing these kind of projects, I stumbled across one experiment which I could not find the explanation of why this happened.

I wanted to show how surface tension works. I had two glasses - one empty and one with colored (purple) water. I then rolled a paper towel to make a rope and submerged one end in water and other in empty glass. I let few hours to go by and after 3-4 hours as I expected water started moving to empty glass. But fun fact was that empty glass started collecting water with green color only. the rope was about half purple and half green. I did not know how this color separation occurred. The tablet I used to color water was a fun bath colored tablet which gets dissolved and changes water color in bath tub for kids. My son had mixed few colors in combination to get to this purple color. He only had a blue, dark purple, and orange tablets. And he probably mixed these in some combination.

After 6 hours, water in green glass started to get purple color and rope also turned full purple. Can anyone explain how initial color separation occurred?

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Re: Color separation

Postby HowardE » Tue Jan 19, 2016 9:40 am

Hi abhishekraut - you've inadvertently discovered 'paper chromatography', a techniques used to separate a mixture into its components.


It's fun to play with. It may be something to explore alongside your child. It's wonderful that you're exposing them to science for fun. Keep up the good work!


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Re: Color separation

Postby bfinio » Wed Jan 20, 2016 6:49 am

Hello abhishekraut,

I would add that Science Buddies has a bunch of projects on chromatography, using paper and other methods, if your son found this interesting and you'd like to try other related experiments:

http://www.sciencebuddies.org/science-f ... graphy&p=1


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