The burning money science trick involves lighting a real bill on fire, but it doesn’t burn and isn’t damaged. The trick demonstrates combustion, alcohol flammability, the high specific heat of water, and the special qualities that distinguish currency from ordinary paper.
All you need for the burning money trick is a genuine bill, either isopropyl alcohol (rubbing alcohol) or ethanol (grain alcohol), water, and a lighter or a match. If you don’t want to hold a burning bill, grab your tongs. Add a pinch of salt to make the normally colorless-to-blue alcohol flame visibly yellow, or any other flame colorant you like.
- Dollar bill (or higher denomination if you’re confident)
- Mixture of 50% alcohol and 50% water (mix equal parts)
- Matches or a lighter
- Salt or other flame colorant (optional)
Mix 95%-99% alcohol in equal parts with water. If you have 70% alcohol, add a splash of water, just to be safe.
Burning Money Without Damaging It
Here’s how to perform the burning money science trick:
- Prepare the alcohol and water solution. You can mix 50 ml of water with 50 ml of 95-100% alcohol.
- Add a pinch salt or other colorant to the alcohol/water solution, to help produce a visible flame.
- Soak a bill in the alcohol/water solution so that it is thoroughly wet. The denomination doesn’t matter, but I tested the trick using $1 before risking $20.
- Use tongs to pick up the bill. Allow any excess liquid to drain. Move the damp bill away from the alcohol-water solution.
- Light the bill on fire and allow it to burn until the flame goes out. The end result is a slightly damp bill. If you’re holding the money and it gets too hot, wave it to extinguish the flame or drop it in water. If you like, soak the bill again and repeat the demonstration.
Real Money vs Paper Money
If you repeat the trick using a piece of regular paper, the paper will burn. Can you guess why?
How the Burning Money Trick Works
There are a few scientific principles at work in this trick:
- Alcohol has a high vapor pressure. While it appears you’re lighting the bill on fire, it’s really the alcohol that’s burning. The high vapor pressure means alcohol quickly evaporates around the bill. What’s left inside the material is surrounded by water. The combustion reaction for alcohol produces carbon dioxide, water, heat, and light:
C2H5OH + 3 O2 → 2 CO2 + 3 H2O + energy
- Alcohol burns at a relatively low temperature. While the flame is hot enough to burn you, it doesn’t reach a high enough temperature to burn the bill because of the insulating effect of the water. If you just doused money with pure alcohol and lit it, it would burn.
- Water has a high specific heat capacity. In other words, water insulates the bill from a temperature change. The alcohol burns off before the temperature gets high enough to burn the money. The flame vaporizes some of the water, but when alcohol burns, it forms even more water.
- The bill is a porous material, more like fabric than paper. Because of its composition, U.S. bills readily absorb liquid (as you know if you’ve ever accidentally washed one). The soaked bill holds a lot of water. On other hand, paper isn’t very porous. A mixture of alcohol and water mainly sits on top of paper, so when you ignite it, it burns.
- Salt colors a flame yellow. Alcohol burns blue, so it isn’t very visible. Adding salt makes the flame more visible, so the trick is dramatic.
This project involves real fire, so it should only be performed by responsible adults. As with any fire project, it’s wise to keep a container of water handy. While you can hold the bill, the fire is hot and can burn you. For safety, it’s better to handle the burning money using tongs. Don’t burn the money over a flammable surface, in case you drop it.
Keep in mind, your mileage may vary depending on your country of origin. The trick works great with U.S. currency, but if your bills are paper or plastic, they might not survive the experience.