Fledge Online / Spring Issue 2011
WHAT’S A FLAME TEST?
April Berlyoung
I
f you ever took a chemistry class in high school or in college, the phrase ‘flame test’ should ring
a bell. It was that test where the teacher finally let you light something on fire, that one where
the dull blue flame would magically transform into miraculous shades of red, green, or white.
This test was, by far, my favorite, perhaps because of crazy lab partners, or maybe because it was the
test that I truly understand inside and out. I have performed the flame test multiple times and have
even assisted in leading this lab with younger students. Although it may seem, and for the most part
is, an easy lab to complete, it’s equally easy to become distracted by the pretty colors or even
perhaps lose control of your inner pyromaniac. My intent is to help make this process both as
mentally and physically painless as possible, and even perhaps enjoyable.
To conduct the flame test, you will first need to gather a few basic materials. You will need a
Bunsen burner, with a hose, to attach to a gas line. A match, or anything that can be used to light a
fire, will also be required. Always take extra precautions when dealing with flame because it can be
very dangerous if not handled carefully. Lighting yourself or others on fire during a lab is one thing
you never want to see happen. The most important items you will need for this test are the solutions
you will be testing. Your instructor will provide you with any number of ionic solutions. These will
need to be close at hand after the Bunsen burner is lit. Finally you will need Q-tips; some lab
manuals call for toothpicks or wooden splints. However, in my experience Q-tips work best for this
sort of test because the cotton fluff at the end of the Q-tip allows more solution to be absorbed.
The more solution that is put in the flame, the longer the color will stay.
To begin your flame test, you must gather all of your materials and set up your Bunsen
burner. Be sure to light your Bunsen burner away from any chemicals; failing to follow this
instruction could lead to an unwanted burst of flame and a few missing arm hairs. After lighting and
adjusting your flame, take one Q-tip, soak it in one ionic solution, and then place it in the flame. The
flame will almost instantaneously change to the characteristic color of the metal ion in the ionic
solution. These results should be recorded in a lab book, and it is best if you are as detailed as
possible in describing the color. You can then go through each of your chemicals, discovering and
recording each particular color. When you have gone through each solution, research the flame test
colors you viewed on the internet; you will find that there are hundreds of sites that will explain
which colors are produced from the metal ions and the associated wavelengths of the light.
One reason why the flame test is my favorite experiment is because of the different colors
produced and how you can literally see the science. The flame test works because of the metal
cations in the ionic solutions. When heat is added to the solutions, the electrons in the metal cations
jump energy levels. As the electrons fall back to their original energy level, they release energy in the
Fledge Online / Spring Issue 2011
form of light. The different colors come from the different wavelengths of light. I have always
found this process interesting and how the specific wavelengths of energy create specific colors.
This experiment has always been fun and interesting to me, not only because of the crazy
colors but because of the associated chemistry. I can only hope that others can find it enjoyable as
well. From crazy lab partners, to just having fun with science, as an aspiring chemist, I hope to
complete this lab many times in the future with more intense solutions. After all, who wouldn’t love
to see awesome colors in a flame and learn about the associated science?
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