Smoke Reaction

A drop of concentrated sulfuric acid added to a pile of potassium chlorate and granulated sugar produces smoke and purplish flame.

Concepts:  Single Replacement Reaction, Exothermic, Re-dox

Time Required:  5 minutes

Chemicals Provided  I6 g potassium chlorate (KClO₃),

         2 g granulated sugar

         1 drop of concentrated [18 M] sulfuric acid, H₂SO₄

Materials:  spatula, eye dropper,  evaporating dish

                                      
Procedure:  With a spatula, carefully mix the potassium chlorate and sugar.  Pile the mixture in the middle of the evaporating dish.  With the spatula, make a small depression in the top of the pile.  Add 1 drop of concentrated sulfuric acid to the depression and stand back. 

     The reaction starts slowly, evolving smoke after 1 - 2 seconds, and then the pile bursts into flame.

Hazards:  Since potassium chlorate is a strong oxidizing agent, mixtures of KClO₃ with combustible materials can be flammable or explosive.  Do not store the mixture of sugar and potassium chlorate.

     Since concentrated sulfuric acid is a strong acid and a powerful dehydrating agent, it must be handled with great care.  Spills should be neutralized with an appropriate agent, such as sodium bicarbonate (NaHCO₃), and then wiped up.

Disposal:  Very little residue remains after this reaction.  After it cools, the solid should be flushed down the drain with water.

Source:  Chemical Demonstrations (Shakhashiri) Vol 1 pg 79

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