Instrumental Methods of Analysis (Flame Emission Spectroscopy) — AQA GCSE Chemistry (Separate)
Modern instruments can identify and measure elements quickly, accurately and from tiny samples.
Why use instruments?
Compared with manual chemical tests, instrumental methods are:
- faster,
- more accurate, and
- more sensitive (they can detect very small amounts of a substance).
They have developed alongside advances in electronics and computing.
Flame emission spectroscopy
Flame emission spectroscopy is used to identify and measure metal ions in solution:
- The sample solution is placed in a flame.
- The light given out (emitted) passes through a spectroscope.
- The output is a line spectrum (a pattern of lines) that is unique to each metal ion, so the metal can be identified.
- The intensity of the spectrum indicates the concentration of the ion.
This method can identify metal ions even in mixtures, where simple flame tests would fail.
Exam tips
- Instrumental methods are faster, more accurate and more sensitive than chemical tests.
- Flame emission spectroscopy identifies metal ions from their line spectra.
- The intensity of the spectrum shows the concentration.
- A key advantage is identifying ions in mixtures and using tiny samples.