Flame Test – Investigating Compounds
To identify the presence of a relatively small amount (ie low concentration) of a metal ion in a compound.
1. Clean a platinum or nichrome wire by dipping it into concentrated hydrochloric acid. 2. Hold the platinum or nichrome wire at the hottest or blue part of a non-luminous Bunsen flame. 3. Repeat until the wire does not produce any colour in the flame (note: do not touch the wire, as salt in sweat will produce an intense sodium flame). 4. Once achieved, dip the nichrome wire in concentrated hydrochloric acid, and then dip it into a small amount of the unknown solid (or solution) to carry out the flame test. 5. Place the wire at the hottest part of a non-luminous Bunsen flame and record the observed colour of the flame.
Compound| Flame Colour|
Sodium Na+| Yellow|
Potassium K+| Lilac|
Strontium Sr2+| Red|
Unknown Compound| Lilac|
Identity of unknown compound: Potassium
Unknown| A| B| C| D| E| F|
Appearance| Black Crystalline| White Crystalline| White crystalline| White crystalline| Grey power| White powder| Melting point| High| Low| High| Medium| High| High|
Solubility in water| Insoluble| Insoluble| Insoluble| Soluble| Insoluble| Soluble| Solubility in ether| | | | | | |
Conductivity of solid| Conducts electricity| Non-conductor| Non-conductor| Non-conductor| Conducts electricity| Non-conductor| Conductivity of solution| Conducts electricity in solution| Non-Conductor| Non-conductor| Non-conductor| Conducts electricity in solution| Non-Conductor| Classification| Ionic bond| Non-polar molecular solid| Covalent bond| Polar molecular solid| Ionic bond| Metallic bond|
No calculations were required in this experiment.
The flame test was undertaken in...