Flame test- By Aditya Abeysinghe

Introduction:

Flame test is an experiment used to identify/distinguish metals using colors exposed to a flame.

Since metallic halides easily evaporate, the test is usually done using the halide components of metals. Out of the halides, chlorides are frequently used because chlorides give a fast change of color when exposed to the flame as opposed to other halides.

Materials needed:

· A rod of platinum, nichrome, asbestos or graphite

· Concentrated HCl solution

· Bunsen burner

· Metallic salt (a chloride of a metal)

· A cobalt glass (if necessary)

Method:

Insert the rod of platinum, nichrome, asbestos or graphite into a concentrated solution of HCl.
Hold the rod to a Bunsen flame. (to the colorless region)
Continue this experiment until the top region of the flame turns colorless.
Form a pulp by mixing the metallic salt with the concentrated HCl solution and apply the pulp to the rod.
Finally, hold the rod to the Bunsen flame and observe the color changes.

Observations:

Note:

Ø If Sodium (Na) is present in minute quantities, the yellow color may be observed as flashes.

Ø Sometimes, the purple color may not be observed for Potassium (K) during the test due to the presence of impurities. However, this problem can be minimized if a cobalt glass is used (cobalt absorbs all colors except Potassium (K).

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