Cannon fire

For people who check facts

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. 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

Place 30cm³ hydrogen peroxide and 20cm³ ethanol into the basin
Surround the basin with screens and light the mixture with the splint. The ethanol will burn with a pale blue or invisible flame
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.