Contact Us

For advice about planning a visit please contact us on 020 7942 4777 or email us.

Teacher News

Receive monthly updates about what's new from the Science Museum to support your teaching.

Burning money demo

 
 

Overview

The underlying science

  • When the money is lit it is the alcohol that burns rather than the money. This is a combustion reaction: alcohol + oxygen --> carbon dioxide + water with the release of heat and light
  • The temperature at which the alcohol burns is not high enough to evaporate the water so the money stays wet and this protects it from catching fire.
  • When the alcohol has all been consumed the flame goes out because there is no more fuel to continue the combustion process.

Materials

  • £5 note, detention slip, or other small but significant piece of paper
  • Isopropyl alcohol (from your chemistry lab or a chemist's shop)
  • Matches, taper or gas lighter
  • Tongs
  • Beaker or saucer
  • 1 teaspoon of salt
  • Water

Practicalities

Because alcohol and fire are involved with this experiment there are a number of health and safety considerations:

  • Isopropyl alcohol is commonly used in secondary school science laboratories but still needs to be handled with care. It can be harmful if inhaled or ingested and can act as a skin irritant. Keep the alcohol in a sealed container until it is used, then handle with gloves and use safety glasses for added protection. Make sure there is effective ventilation in the room you are using.
  • Use long-handled matches or tapers to ensure that the flame is held well away from students' hands. Ensure that they use tongs to hold the soaked note and hold it at arm's length over a flameproof surface. The alcohol will burn off very quickly leaving the damp note, so this should minimise the risk. Because there is little smoke produced the experiment may be performed relatively close to a fire alarm (about 1 metre away) without setting it off.
  • The flame is more impressive if the light levels of the room can be reduced.

Discussion

  • Why doesn't the note burn?
  • What is the role of each of the ingredients in this trick?