School Science/Cannon fire

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Cannon fire is an audio experiment that produces a series of crackles and bangs like gunfire. The noises are produced by hydrogen peroxide and potassium manganate(VII) reacting to produce oxygen which increases the rate of burning of the ethanol.

Safety[edit]

  • Wear eye protection / full face shield
  • Remove any concentrated sulfuric acid from the area when using potassium manganate(VII)
  • Avoid inhaling any vapour produced
  • Be aware of the pale blue / invisble flame that is produced by the burning ethanol

Required[edit]

  • Heatproof surface
  • Large evaporating basin or metal plate
  • Safety screens
  • Splints
  • Hydrogen peroxide (20%)
  • 0.5 g potassium manganate(VII)
  • Ethanol

Method[edit]

  1. Place 30 cm3 hydrogen peroxide and 20 cm3 ethanol into the basin
  2. Surround the basin with screens and light the mixture with the splint. The ethanol will burn with a pale blue or invisible flame
  3. Sprinkle 0.5 g of potassium manganate(VII) into the dish

Notes[edit]

  • A fine powdered potassium manganate(VII) will give lots of bangs that are fairly quiet. Coarse powdered potassium manganate(VII) however, will give fewer, louder bangs.

It's worth while covering the benches with heatproof mats or such like, this one can go off. I love it!