School of Mathematics and Natural Sciences

Flame Coloration by Alkali and Earthalkali Metal Compounds



Hydrochloric acid, c = 1 mol/L - WARNING


Lithium chloride - WARNING

H302, H315, H319
P302+P352, P305+P351+P338

Sodium chloride

Not a dangerous substance according to GHS

Potassium chloride

Not a dangerous substance according to GHS

Calcium chloride - WARNING


Strontium chloride - DANGER

H315, H318, H335
P261, P280, P305+P351+P338

Barium sulfate

Not a dangerous substance according to GHS

For each of the following samples a magnesia rod is dipped into diluted hydrochloric acid and held into a burner flame until there is no visible flame coloration. The magnesia rod is then coated with diluted hydrochlorid acid and a sample of one of the following salts is applied to it: lithium chloride, sodium chloride and potassium chloride as well as calcium chloride, strontium chloride and barium sulfate. The rod with the sample is then held into the flame of a gas burner.

The flame takes on a characteristic color, starting with carmine red (lithium, strontium), then yellow (sodium), orange (calcium) and green (barium) up to violet (potassium). Especially the violet color from potassium salts can be observed far better viewing it through a cobalt glass.

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