Table of Contents
Okay, picture this. You are hanging out in your backyard. You take a normal scoop of white powdered sugar from the kitchen, mix it with a tiny bit of baking soda, and pour it onto a pile of sand. It looks incredibly boring. It just looks like white dust sitting in the dirt.
Then, you take a lighter and ignite the white dust.
Instantly, the powder turns pitch black. But it doesn’t just burn up and vanish like paper. It starts to grow. And grow. And grow. The tiny spoonful of sugar violently stretches upward, twisting and curling into a massive, thick, foam-like black snake that gets almost a foot long! It literally looks like a terrifying monster is crawling straight out of the sand.
How in the world does a tiny scoop of sweet sugar turn into a giant, horrifying black worm? Let me break down the crazy combustion physics of the classic Black Snake.
The Secret Ingredient is Carbon
To understand where the giant snake comes from, we have to look inside the sugar.
Sugar is a carbohydrate. That big word literally means it is made of carbon atoms and water (hydro) atoms. Normally, those atoms are locked together perfectly, which is why sugar looks white and tastes sweet.
But when you introduce the sugar to a roaring fire, you absolutely wreck those chemical bonds. The intense heat causes the water atoms inside the sugar to instantly turn into steam and boil away into the air.
What is left behind? The carbon.
When carbon is left totally alone, it turns jet black. (This is exactly why your marshmallows turn into black charcoal if you leave them in the campfire for too long!). So, the fire strips away the water, leaving a massive puddle of black, burnt carbon. You can read all about the intense thermal breakdown of carbohydrates over at the American Chemical Society (ACS).
The Baking Soda Balloon
Okay, so the sugar turns into black carbon. But why does it grow into a giant snake? Why doesn’t it just stay in a flat black puddle on the sand?
This is where the baking soda steps in to save the day.
Baking soda has a secret superpower: when it gets really, really hot, it violently releases Carbon Dioxide (CO2) gas.
So, let’s put it all together. The sugar is burning and turning into a thick, gooey puddle of black carbon. At the exact same time, the baking soda is getting hot and blasting out invisible CO2 gas.
The CO2 gas tries to escape into the air, but it gets trapped inside the gooey black carbon! The gas pushes upward, inflating the black carbon exactly like a giant black balloon. As more sugar burns, more gas pushes up, forcing the black snake to stretch higher and higher into the air until it cools down and turns solid.
If you want to read more about how expanding gases create physical pressure, the brilliant physics minds at the Institute of Physics (IOP) have incredible resources.
A Safer Pharaoh
If this sounds super familiar, it’s because this is actually the safe, homemade version of the legendary “Pharaoh’s Serpent.”
Back in the 1800s, people used a crazy toxic chemical called Mercury(II) thiocyanate to make yellow snakes that grew ten feet long! But breathing in mercury vapor can cause extreme brain damage, so they literally banned the toy.
The Black Snake uses the exact same expanding-gas physics, but uses harmless kitchen sugar instead of toxic heavy metals. It is the ultimate backyard science hack! If you want to read the terrifying history of why they banned the toxic mercury versions, the Centers for Disease Control and Prevention (CDC) has the full history on heavy metal poisoning.
Doing it at Home
Because this experiment involves literal fire, you absolutely must do this outside on concrete or dirt. Never do this inside your house!
You will need to soak your pile of sand in lighter fluid so the sugar has enough heat to cook. Because you are messing with lighter fluid, you need a long-reach Heavy Duty BBQ Lighter so your hands are nowhere near the flames. And since you are essentially making a campfire, having a small Home Fire Extinguisher sitting nearby is just smart science.
For more incredibly fun outdoor combustion experiments, definitely check out the massive project list at Science Buddies.
Quick Black Snake Summary
What you need:
– 4 parts powdered sugar (confectioners sugar works best!)
– 1 part baking soda
– A bucket of playground sand
– Lighter fluid or high-percentage rubbing alcohol
– A long-reach lighter
Step-by-step guide:
1. Mix the powdered sugar and baking soda together in a small bowl. Stir it up perfectly.
2. Go outside and pour a pile of sand onto the concrete. Make a small dent in the top of the sand pile.
3. Squirt some lighter fluid directly into the dent in the sand.
4. Pour your sugar and baking soda mixture onto the wet sand.
5. Use your long lighter to ignite the sand.
6. Stand back and watch the sugar burn, expand, and grow into a massive black carbon snake!
10 Carbon Brain Teasers
Think your brain is burning with knowledge? Try to answer these 10 riddles!
1. The Riddle: I am the sweet, white powder that acts as the main fuel for the snake. What am I?
The Answer: Sugar.
2. The Riddle: I am the pitch-black element that is left over after the fire burns all the water out of the sugar. What am I?
The Answer: Carbon.
3. The Riddle: I am the kitchen ingredient you mix with the sugar that blasts out invisible gas when I get hot. What am I?
The Answer: Baking soda.
4. The Riddle: I am the invisible gas created by the baking soda that inflates the black carbon like a giant balloon. What am I?
The Answer: Carbon Dioxide (CO2).
5. The Riddle: I am the gritty, dirt-like material you use to build a safe, fireproof base for your experiment. What am I?
The Answer: Sand.
6. The Riddle: I am the highly toxic, dangerous metal used to make the original 1800s version of this snake before it was banned. What am I?
The Answer: Mercury.
7. The Riddle: I am the flammable liquid you squirt onto the sand to make sure the fire burns hot enough to cook the sugar. What am I?
The Answer: Lighter fluid.
8. The Riddle: I am the long, handheld tool you use to safely ignite the pile without burning your fingers. What am I?
The Answer: A BBQ lighter.
9. The Riddle: I am the safety device you should always keep nearby just in case your outdoor fire gets out of control. What am I?
The Answer: A fire extinguisher.
10. The Riddle: I am the fancy science term for the violent process of burning something with fire. What am I?
The Answer: Combustion.
The Wrap Up
The Black Snake is basically a masterclass in how to trap gas. You take the pure carbon from burnt sugar, and you inflate it from the inside using baking soda. It is simple, it is cheap, and it looks like a crazy special effect from a movie.
If you want to read more about how carbon makes up almost everything on earth (including you!), you should totally bookmark National Geographic Education. Now grab some sugar, go outside, and start summoning some carbon monsters!
Cited Sources & Evidence
- American Chemical Society (ACS)
- Institute of Physics (IOP)
- Centers for Disease Control and Prevention (CDC)
- Science Buddies
- National Geographic Education