Burning money

In this activity you can set fire to a £5 note without damaging it, all thanks to the properties of liquids.

Year groups: 7-9 (ages 11-14)

Educational objective

To see how liquids in a solution can have different properties and react differently, i.e. whether or not they combust.

Key student learning

Solids can dissolve in liquids; solid, liquids or gases can combine to form solutions.
The two liquids in a solution can be separated because they have different properties.

Materials needed, per student

Detention slip, £5 note 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?

Extensions

" If you are feeling very confident this is a great lesson starter if you use a higher denomination note. This trick can also be done with an exam paper to celebrate the end of National Tests!
" Experiment with different alcohols or add substances to see if they alter the colour of the flame (you may want to use paper instead of a bank note during this experimentation).
" Try with other objects soaked in the solution (we've tested it on plastic, cloth and paper, but make your own careful tests before using anything of value).

Links to everyday life

Fractional distillation is used in the petrochemical industry to refine crude oil, among other applications. However, secondary students will most often come across it in classroom experiments.

Launchball links

Launchpad

Educators' Information