Make a Fire Snake

Introduction

With a few simple ingredients, you can create a "fire snake" that appears to grow out of nowhere in this fun experiment! Although it looks magical, no magic is involved—it is all because of a chemical reaction. Try it to find out how it works!

Credits

Ben Finio, PhD, Science Buddies

Svenja Lohner, PhD, Science Buddies

• Sand
• Baking soda
• Sugar
• Small ceramic plate or bowl
• Small cup
• Measuring spoons
• Lighter fluid
• Long lighter or matches
• Adult supervision
• Bucket of water or hose
  
  

Prep Work 

1. This experiment requires dry sand. Your sand might be damp if you get it from somewhere that is in contact with the ground, like a sandbox. If needed, spread your sand out on a baking tray and place it in direct sunlight or in the oven until it is completely dry. 
2. Only do this experiment with adult supervision, in a location where it is safe to have a small fire. Have a fire extinguisher accessible for emergencies. 

Procedure

1. Fill your plate or bowl with sand.
2. Soak the sand in lighter fluid. 
3. Mix 1 tbsp baking soda with 4 tbsp sugar. 
4. Pour the sugar/baking soda mixture into a pile on top of the sand.
   
5. Use matches or a lighter to ignite the lighter fluid. 
6. Watch closely, and be patient. The reaction may be slow to start. 
   
   What happens? Keep watching until it stops growing!
   
   
7. 
8. Wait at least 10 minutes after the flames stop for your fire snake to cool. Have an adult make sure it is no longer hot, then you can touch it. 
   
   What does it feel like?
   

Cleanup

Douse your fire snake and sand in water to make sure there are no remaining flames, then it is safe to dispose of all the materials in the trash. 

What Happened?

When you set the lighter fluid on fire, the sugar and baking soda mixture also started to burn. As it burned, it created gas bubbles that got trapped, resulting in the black "snake" structure that rose out of the flames. The snake grows slowly, and may take 10–20 minutes to reach full size. It might be surprising that the snake is so bigand seemingly comes out of nowhere, but if you wait until it cools and then poke it or pick it up, you will see that it is extremely lightweight, like foam. See the Digging Deeper section to learn more about the chemical reaction that creates the fire snake.

Digging Deeper

Table sugar, also called sucrose, is a chemical compound that contains lots of carbon. Its chemical formula is C12H22O11. Sugar can be oxidized, which means that it can react with oxygen to form other products. When you expose sugar to an open flame, it will burn quickly and react with the oxygen in the air. This is called a combustion reaction. The end products are carbon dioxide (CO2) and water (H2O). A different reaction happens if there is not enough oxygen present during the combustion to form CO2. In this case, the sugar decomposes, resulting in elemental black carbon (C), or charcoal. 

The baking soda (sodium bicarbonate, NaHCO3) decomposes at high temperatures and releases lots of CO2. The production of high amounts of CO2 causes a lack of oxygen. This means that there is not enough oxygen for all the sugar to be converted into CO2 and water via a combustion reaction. Instead, some of the sugar decomposes into elemental carbon and starts forming the solid black snake-like structure. The carbon dioxide gas and water vapor push the sugar and baking soda mixture upwards. At the same time, these gases get trapped in the solid carbon, creating the lightweight foam snake that you see emerging from the sand.