Video:How to Conduct a Flame Testwith Dr. Anne Marie Helmenstine
A flame test can help visually determine an unknown metal's identity. Learn how to conduct a flame test and what the different colored flames indicate.See Transcript
Transcript:How to Conduct a Flame TestThe flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a Bunsen burner. The heat of the flame converts the metal ions into atoms which become excited and emit visible light. The characteristic emission spectra can be used to differentiate between some elements. There are two different ways to do a flame test.
Wire Loop Flame TestThe first is the classic wire loop method. First, you need a clean wire loop. Platinum or nickel-chromium loops are most common. The loop must be cleaned between tests. The clean loop is dipped in either a powder or solution of an ionic (metal) salt. The loop with sample is placed in the clear or blue part of the flame and the resulting color is observed.
Wooden Splint/Cotton Swab Flame TestThe second method to do a flame test is by wooden splint or cotton swab. Wooden splints or cotton swabs offer an inexpensive alternative to wire loops. To use wooden splints, soak them overnight in distilled water. Pour out the water and rinse the splints with clean water, being careful to avoid contaminating the water with sodium (such as from sweat on your hands).
Take a damp splint or cotton swab that has been moistened in water, dip it in the sample to be tested, and wave the splint or swab through the flame. Do not hold the sample in the flame as this would cause the splint or swab to ignite. Use a new splint or swab for each test. The sample is identified by comparing the observed flame color against known values from a table or chart.
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