Flame emission spectroscopy
|Flame tests can be used to identify some metal ions (cations).|
Lithium, sodium, potassium, calcium and copper compounds produce
distinctive colours in ﬂame tests:
• lithium compounds result in a crimson ﬂame
• sodium compounds result in a yellow ﬂame
• potassium compounds result in a lilac ﬂame
• calcium compounds result in an orange-red ﬂame
• copper compounds result in a green ﬂame.
how to perform a flame test
- Prepare wire loop, beaker of water and burner.
- Heat the wire loop until it glows before dousing it in the water to cool it off. repeat this until the loop does not impart any colour to the flame.
- Use tongs pick up the loop and place your mixture or compound on the loop.
- Insert loop and mixture into the flame and observe the flames colour.
The image on the left shows the line spectra for some elements.
The image below shows a continuous spectrum.
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