Ask A Scientist General Science Archive

name         Stan C.
status       student
age          40s

Question -   My son is doing his science fair project on "Bleach,
Where Does The Color Go". There was a pretty good explanation of the
process involved, in the chemistry archive. Can you help us with some
experiments that show the process at work, and some type of visual aids
that graphically demonstrate the process.Thank you very much and I'm very
glad that I have found your site it is very interesting.
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I assume you mean "household bleach" (sodium hypochlorite) and not
hydrogen peroxide, or other peroxide bleaches. They each behave somewhat
differently because each depends upon it particular oxidation reaction. For
example, hydrogen peroxide is very effective in "bleaching" a fresh blood
stain.
    Some comparisons that could be made are to use various food colors;
various vegatable dyes (red cabbage, beets, blueberries, black berries,
cherry). The effect of temperature could be examined by using warm bleach,
say at 60C, room themperature 25C, and 0C (ice). Various fabrics could be
compared.
    A very interesting one (I think) would be to examine whether or not
"bleach" has any effect on fabric "whiteners" -- these are substances added
to detergents that fluoresce just outside the visible spectrum on the
ultraviolet side. A "black light", that is available in most hobby stores or
in any mineral collectors supply house, shows the fluoresence of these
substances very sensitively. I don't know the answer, so I can't give you
the answer -- but that's what research is all about!! The "black light" may
also cause other dyes to respond and the disappearence of the color and the
fluorescence could be compared. Hope this helps.

Vince Calder
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