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Unformatted text preview: ed to test for its presence. When the material is excited by placing it in a flame, the procedure is called
a flame test. This simple approach is often useful in identifying materials.
The emission spectra of gaseous
elements can be observed by exciting the atoms in a gas filled tube with high voltage and viewing the light from
the glowing gas with a spectroscope. The spectroscope separates the emitted light so that you can see the
www.webassig n.net/ebooks/wsug encheml1/lab_2/manual.html 3/6 4/15/13 Lab 2 - Flame Tests individual wavelengths that contribute to the visible color of the emission. The result is called a line spectrum. The
component of the spectroscope that separates the light into its component wavelengths is usually a prism or
diffraction grating, and is often called a monochromator.
Similar instruments are used to measure light that is
absorbed or transmitted by a substance. A common instrument used for this purpose is a spectrophotometer,
also called a colorimeter or spectrometer. Instruments of this type can measure both the amount of light
transmitted by the sample (T or %T) or the absorbance of...
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