Cannon fire

This 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. These increase with the rate of burning of the ethanol.

Table of contents 1 Safety 2 Required 3 Method 4 Notes

Safety

• Wear eye protection / full face shield
• Remove any concentrated sulphuric 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

• Heatproof surface
• Large evaporating basin[?] or tin plate
• Safety screens
• Splints
• 20 vol hydrogen peroxide
• 0.5 g potassium manganate(VII)
• Ethanol

Method

1. Place 30cm³ hydrogen peroxide and 20cm³ 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

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