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Name:  Heidi
Status: student
Grade: 9-12
Location:MD
Country: N/A
Date: 2/6/2005


Question:
How can one determine that there is more chlorine in 8oz of tap water than in 8oz of distilled water? A simple experiment would be best (other than test strips), but any suggestions are helpful.


Replies:
Swimming pool stores have inexpensive, but accurate kits for determining the chlorine content in swimming pools. These are much better than "test strips" and pretty simple to use. There is also a procedure using the reaction of "available" chlorine (hypochlorite) to oxidize iodide ion to I2 and measuring the color with a starch solution. Do a "Google" search for "iodide method available chlorine" for details. However, reducing the procedure to actual use will involve a lot more time and effort. I would recommend the pre-packaged pool test kits.

Vince Calder


Heidi,

Your question brings back memories as this is one experiment that I did in high school chemistry. You will have to do a bit of research on this because I do not remember the reagents needed. The test is similar to testing pool water. You take your sample, add a reagent and then test the sample using a spectraphotometer. The reagent produces a color which is measured at a certain wavelength of light. The more chlorine, the darker the color and more light absorbed. You start by creating a graph using known concentrations of Chlorine. Then you measure your samples.

Have fun

Bob Hartwell



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