Spectrometer Used in Chemistry
by Ron Kurtus (17 April 2013)
A spectrometer is a device that can be used in Chemistry to determine what elements are involved in a burning or heated material.
The nature of the light emitted from a heated material provides a "fingerprint" of what elements are involved. Each element has a unique set of spectral lines.
Examination of the spectral lines is used to determine which elements are involved, as well as how many elements are in a compound.
Questions you may have include:
- What does a spectrometer do?
- What is the spectrum of an element like?
- How does a spectrometer determine chemical composition?
This lesson will answer those questions.
Spectrometer spreads light waves
A spectrometer is a scientific instrument that uses glass prism or diffraction grating to spread an incoming beam of light into its spectrum. The different parts of the spectrum can then be measured as to its wavelength and intensity.
In Chemistry, the light from a burning or heated material can be spread into its spectrum and examined to determine the elements involved. Spectrometers are also used in Astronomy to determine the materials on distant stars.
(See Spectrometer Useful in Astronomy for more information.)
Elements have unique spectral lines
A heated element gives off light in a spectrum or range of colors. However, the light is not a continuous band of colors but instead is a series of spectral lines that are unique to the element.
Hydrogen spectral lines
Sodium spectral lines
Determines chemical composition
By using a spectrometer and measuring the wavelengths of the spectral lines, you can determine what materials are being heated. The intensity of the spectral line also gives an indication of the amount of the element in the object.
A good example can be seen by sprinkling table salt (Sodium Chloride or NaCl) in a candle flame. The flame turns yellow, because of the two strong yellow spectral lines of Sodium, as seen in the picture above.
By knowing the spectral lines of the various elements, you can determine what the chemical composition is of the material. However, it can be difficult to separate out all the spectral lines when examining a complex material.
A spectrometer uses a prism or diffraction rating to spread out a incoming beam of light into its spectrum of different colors or wavelengths. Since each element has a unique set of spectral lines, examination of the spectral lines is used to determine which elements are involved, as well as how many elements are in a compound.
Be clever by using the right tools
Resources and references
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Spectrometer Used in Chemistry