8.3.6

Methodology for Chemical Analysis

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Instrumental Methods of Chemical Analysis

Modern technology provides us with very accurate instruments that we can use to detect and analyse elements and compounds. Instrumental methods have advantages and disadvantages compared to traditional methods:

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Advantages of instrumental methods

  • Greater sensitivity and accuracy.
  • Quicker at producing results.
  • Able to analyse tiny samples.
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Disadvantages of instrumental methods

  • The instruments are often expensive.
  • You need to go through special training to operate the instruments.
  • The results are often only useful when compared to data from known substances.

Flame Emission Spectroscopy

Flame emission spectroscopy is an instrumental method of identifying metal ions in a solution and their concentrations. This method has advantages and disadvantages compared to traditional methods:

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Advantages

  • More sensitive and accurate.
  • Quicker at producing results.
  • Able to analyse small samples.
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Disadvantages

  • The instruments are often expensive.
  • You need to go through special training to operate the instruments.
  • The results are often only useful when compared to data from known substances.
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Spectroscopy process

  • Place a sample of a metal solution into a flame. Light is emitted.
  • The light that is emitted is captured by a spectroscope.
    • This instrument can distinguish between different wavelengths of light to produce a line spectrum.
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Spectroscopy analysis

  • We can analyse the line spectra produced by flame emission spectroscopy to see which metal ions are present.
  • We can use the data to work out the concentration of the metal ions.
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Identifying metal ions

  • Each metal ion will generate a distinct line spectrum. This means that we can identify all ions present in a solution.
  • The intensity of line spectra gives information about the concentration of an ion.
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Reference spectra

  • Unlike flame tests, flame emission spectroscopy allows us to analyse mixtures by comparing them with reference spectra.

Jump to other topics

1Atomic Structure

2Chemical Bonding

3Quantitative Chemistry

4Chemical Changes

5Energy Changes

6The Rate & Extent of Chemical Change

7Organic Chemistry

8Chemical Analysis

9Chemistry of the Atmosphere

10Using Resources

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