Equipment and Method

🧪 Equipment and Method

Equipment Needed

• Bunsen burner — provides the heat energy
• Nichrome wire loop — holds the sample (nichrome is unreactive and melts at very high temperature)
• Dilute hydrochloric acid (HCl) — cleans the wire between tests
• Sample of metal compound — the substance to be identified
• Safety goggles — essential eye protection

Why Nichrome Wire, Not Iron Wire?

The flame test wire must be nichrome (a nickel-chromium alloy) or platinum — never iron wire. Iron wire is unsuitable because iron oxidises in the flame and produces its own orange-brown colour, which contaminates the result and masks the true flame colour of the sample. Nichrome is chosen because it is unreactive, has a very high melting point, and does not produce a visible flame colour of its own. Some older textbooks refer to a "wire loop" without specifying the material — if asked in an exam, always state nichrome wire.

Step-by-Step Method

1. Dip the nichrome wire loop in dilute HCl
2. Hold in the blue Bunsen flame until no colour is seen (wire is clean)
3. Dip the clean wire in HCl again, then into the sample
4. Hold the wire with sample in the blue Bunsen flame
5. Observe and record the flame colour immediately
6. Clean the wire thoroughly before testing the next sample

Important: Use the blue flame (fully open air hole) — it is the hottest part of the Bunsen flame and gives the clearest results.