Method
- First sterilise the nichrome wire by dipping in
and burning on a bunsen burner until no colour remains. - Place a small amount of unknown chemical on nichrome wire.
- Place wire into blue bunsen burner flame.
- The colour of the flame can be used to identify the metal ion present.
Results
| Metal | Colour |
|---|---|
| Lithium | Crimson |
| Sodium | Yellow |
| Potassium | Lilac |
| Calcium | Oranges-Red |
| Copper | Green |
Problems with Flame Test
- Colour of flame difficult to distinguish for low concentrations.
- Mixture of metal ions can mask the colour of the flame.
Flame Emission Spectroscopy
- A sample of the metal ion is placed onto a flame.
- The light given out is passed onto a spectroscope
- The machine converts light into a line spectrum
- Positions of lines in the spectrum are specific for a give metal ion
- Also tells us the concentration based on line intensity
This is an example of an Instrumental Method 1. IM IMs are:
- Rapid
- Sensitive
- Accurate