Ask A Scientist© Chemistry Archive

name        Theodore W.
status      educator
age         40s

Question -  Using a 3/4 inch copper tube drill several 1/4 inch holes
through the pipe. Now a rubber hose is inserted and the device is thrown
into a campfire. The result is brilliant colors in the blue range. There
is also some purple and yellow at times. What exactly causes this
reaction? What exactly causes the flames to be colored.
Please explain this so that a 7th grade student working on a science fair
project can understand the answer.
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Mr. Wunderle,

I suspect the rubber hose is simply an additional source of fuel and
contaminants that make the pipe hot enough to allow the emission spectrum of
copper to be produced. The holes in the pipe provide increased surface area on
which a chemical reaction can occur. In addition, it provides more places for
the reaction to make itself visible.

Copper ions can impart a pretty blue and green color to a flame. If the hose
insert was made of plastic, the plastic might contain chlorine. The presence
of chlorine e allows the copper to form copper chloride which is a volatile
compound that offers a brilliant copper ion spectrum.

The purple and yellow colors are doubtless due to the emission spectrum of
other elements -- possibly potassium and sodium.

Go here for additional information:

http://146.139.100.40/webpages/askasci/chem00/chem00173.htm

Regards,
ProfHoff
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Flame tests operate on the premise that compounds of certain metals are
volatilized in a non-luminous  flame and give off characteristic colors to
the flames. Some colors are listed below.

           Sodium: golden-yellow
           Potassium: violet (lilac)
           Lithium: carmine-red
           Calcium: brick-red (yellowish)
           Strontium: crimson
           Barium, molybdenum: yellow-green
           Borates, copper, thallium: green
           Lead, arsenic, antimony, bismuth, copper: blue

Dr. Harold W. Myron
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