Description

A test tube containing four differently colored layers is placed in a beaker of sand. The reaction, started with a drop of sulfuric acid, produces an intense flame, heat, and smoke, and the flame gives off different colors as it burns through the layers.

Explanation

In this demonstration the "fuel" is a mixture of potassium chlorate (KClO₃), an oxidizer, and sugar (C₁₂H₂₂O₁₁), the actual fuel. When ignited with a drop of sulfuric acid, the combustion of the sugar is accelerated by the potassium chlorate, producing a rapid burn and intense heat.

The fuel is arranged in layers, with each layer containing one of the substances listed below. With the intense heat of the flame, the metals in these substances are vaporized, producing atoms in an excited state. When these atoms relax, they give off light of a characteristic wavelength. The first layer, containing no additional substance, gives a white flame. The second layer contains iron (Fe) filings, which produce yellow sparks. The cupric chloride (CuCl₂) in the third layer produces a blue flame, and the strontium nitrate (Sr(NO₃)₂) in the fourth layer gives a red flame.

These are some of the same substances used in fireworks!

“Fuel”: KClO₃ and sugar (C₁₂H₂₂O₁₁)

Layers:	nothing	colorless (white)
	Fe filings	yellow
	CuCl2	blue
	Sr(NO3)2	red

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explanation furnished by UCCS's Dr. David Anderson