Lycopodium Powder "Explosion"
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|  Yüklə 28 Kb.
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Surface Area and Reaction Rate: Lycopodium Powder "Explosion" Description: Lycopodium powder is shown to be combustable when sprinkled onto a flame. A lit match comes in contact with a pile of lycopodium on a watch glass with little results. The same amount of powder is dumped into a cardboard tube with a lit candle at the bottom, and the result is a column of flame. Concept: A fine mist of dust can be highly flammable because of the high surface area of the combustible (the dust) to the oxidizer (the air). The rate of reaction is proportional to surface area. Materials:
Safety: Wear safety goggles and thermal gloves. Use an amount of lycopodium powder that you are comfortable with. Be sure the practice this demonstration a few times before attempting it in front of a class. Procedure: Fold the notecard in half and put a small amount of lycopodium in the groove that is created. Light the candle and set it onto a tabletop that is a good distance away from any students of flammable materials. Dump the contents of the note card into the flame. The powder should burst into flames. Pile a similar amount of powder onto a watch glass and touch a lit match to the surface. Small amounts of powder will produce some sparking, but the majority of the pile will not combust. Pour the contents of the watch glass into the note card. Light the candle and set it onto the floor. Cover the candle with the cardboard tube and dump the powder (from arms length) from the note card into the tube. A column of flame should quickly burst from the top of the tube. Clean Up: Clean the excess lycopodium from the countertop and floor using the squirt bottle and paper towels provided, or inform the demonstration technician that this needs to be cleaned up. 13-7 |