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ExposeExciteIgniteMay2012

6. Wear ear and eye

6. Wear ear and eye protection and caution all in the room to protect their ears. All have to stand at least 5 meters off. This includes you! Have all do a countdown and then touch the speaker wire for 3 seconds to the battery. BOOOM !! Wire to 9V battery Figure 4.16 What is happening here? If you ever had the chance to open up a cherry bomb or any other type of firecracker, then you will know that it contains very small quantities of chemicals. The secret of getting the amplified bang from fireworks, lies in the strength of the packaging. When a detonation occurs, the shock wave is amplified hundredfold by simply restricting the rapidly expanding gas volume. The restriction causes secondary detonations, a huge increase in heat and pressure through chain reactions and the end result is the destructive explosion. In the armaments and atomic bomb industries the packaging of the firepower is as important as the chemical composition of the explosives. Extension If you have access to firecrackers, wear safety gear and carefully open one. Place the dry powder on a heat pad / tile. Wear safety gear and simply light one end of the pile with a fire lighter. It should cause a small bright flash but no loud sound. Then take a second firecracker outside, light its fuse and experience the bang. Same chemicals, different packaging. Amazing! Key Terms Hydrogen chemistry, exothermic reactions, buoyancy, Boyle’s Law References 1. An “Egg-Splosive” Demonstration, Becker, R., J Chem Educ, 1992, 69 (3), p 229 - 230 47

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