Quicksand Goo Experiment – Cornstarch Science Activity
Mix up a batch of gooey material that behaves just like real quicksand.
Quicksand Goo Experiment: Cornstarch Science Activity
Mix up a batch of gooey material that behaves just like real quicksand in this easy cornstarch activity that is a fun lesson in viscosity!
Anyone who has ever watched a classic Western knows about the dangers of falling into a pit of quicksand — you know, that gooey stuff that grabs a hold of its victim and swallows him alive! So, what is quicksand and how does it really work? In this experiment, you’ll use ordinary cornstarch to model the behavior of real quicksand. With our Quicksand Goo Experiment, you’ll learn how to make quicksand in your own kitchen.
- One box of cornstarch (16 oz)
- Large mixing bowl
- Cookie sheet, square cake pan, or something similar
- Pitcher of water
- Gallon size zipper-lock bag
- Newspaper or a plastic drip cloth to cover the floor
- Food coloring
Pour approximately one-quarter of the box (about 4 ounces) of cornstarch into the mixing bowl and slowly add about 1/2 cup of water. Stir. Sometimes it is easier (and more fun!) to mix the cornstarch and water with your bare hands.
Continue adding cornstarch and water in small amounts until you get a mixture that has the consistency of honey. It may take a little work to get the consistency just right, but you will eventually end up mixing one box of cornstarch with roughly 1 to 2 cups of water. As a general rule of thumb, you’re looking for a mixture of roughly ten parts cornstarch to one part water. Notice that the mixture gets thicker, or more viscous, as you add more cornstarch.
Sink your hand into the bowl of “quicksand” and notice its unusual consistency. Compare what it feels like to move your hand around slowly and then very quickly. You can’t move your hand around very fast. In fact, the faster you thrash around, the more like a solid the gooey stuff becomes. Sink your entire hand into the goo and try to grab the fluid and pull it up. That’s the sensation of sinking in quicksand!
Drop a plastic toy animal into the cornstarch mixture and then try to get it out. It’s pretty tough even for an experienced quicksand mixologist.
How Does It Work
Cornstarch is a common kitchen pantry item that is used as a thickening agent in many different food dishes, including sauces, gravies and soups. It’s made from the endosperm of corn and is also commonly called “cornflour.”
When cornstarch is mixed with water, it’s sort of like magic: sometimes it acts as a solid and sometimes it behaves as a liquid. Why? This concoction is an example of a suspension (a mixture of two substances): one substance is finely divided and dispersed into another. In the case of the cornstarch quicksand, it’s a solid dispersed into a liquid.
When you slap the cornstarch quicksand, you force those long starch molecules closer together. The impact of this force traps the water between the starch chains to form a semirigid structure. When the pressure is released, the cornstarch will flow again.
The Quicksand Experiment: A Lesson in Viscosity
All fluids have a property known as “viscosity.” Viscosity is the measurable thickness (or resistance) in a fluid. Honey and ketchup are liquids that have a high resistance to flow, or a high viscosity. Water has a low viscosity. Sir Isaac Newton said that viscosity is a function of temperature. So, if you heat honey, the viscosity is less than that of cold honey. The cornstarch-water mixture (as well as real quicksand) are both examples of non-Newtonian fluids. That’s because their viscosity changes when stress or a force — not when heat — is applied.
What is Quicksand?
But what is quicksand — really? Quicksand is nothing more than a soupy mixture of sand and water; the sand literally floats on the water’s surface. Quicksand is just solid ground that has been liquefied by too much water. The term “quick” refers to how easily the sand shifts in this solid-liquid state. Quicksand is created when water floods or saturates an area of loose sand and the sand begins to move around. When the water in the sandy soil cannot escape, it creates a liquid-like soil that can no longer support any weight. If an excessive amount of water flows through the sand, it forces the sand particles apart. This separation of particles causes the ground to loosen; thus, any weight that is placed on the sand will begin to sink through it.
What Causes Quicksand?
The quicksand phenomenon can be caused by flowing underground water that rises to the surface, or even by an earthquake that agitates the sand. You are likely to find quicksand around riverbanks, lake shorelines, marshes, beaches, near underground springs or any other place where an uprising of water oversaturates and agitates the sand.
The next time you stand barefoot on a beach, think about the properties of quicksand. Normally, the grains of wet sand are tightly compressed together. This firm ground easily supports your weight. The friction between the grains of wet sand is strong enough to make it easy to build sandcastles. However, when the sand on the beach is flooded with an excess amount of water, the agitated sand particles begin to move, separate and quickly wash away — right out from under your feet!
Take It Further
Pour the cornstarch mixture onto a cookie sheet or in a cake pan. Notice its unusual consistency as you pour it onto the pan. Stir it around with your finger — slowly at first, and then as fast as you can. Skim your finger across the top of the glop. What do you notice?
Next, try to roll the fluid in between your palms to form a ball. You can even hold your hand flat over the top of the pan and slap the liquid glop as hard as you can. Most people will run for cover as you get ready to slap the liquid, fearing that it will splash everywhere. According to our theory, the mixture should stay in the pan. Yeah, right! If your cornstarch-water mixture inadvertently splatters everywhere in this cornstarch experiment, you will know you need to add more cornstarch. When you are finished, pour the cornstarch glop into a large zipper-lock bag for later use.
IMPORTANT - Read This!
The cornstarch will not stay mixed with the water indefinitely. Over time, the grains of the cornstarch will separate from the water. It will then form into a solid clump at the bottom of the plastic storage bag. For this reason, DO NOT pour this mixture down the drain. It will clog the pipes and stop up the drain (and your mom or dad will be pretty upset). Pour the mixture into a zipper-lock bag and dispose of it into the garbage.
How to Make Quicksand on The Ellen DeGeneres Show
n an effort to live out our mission (“Make It Big, Do It Right, Give It Class!”), we took our Quicksand Goo Experiment to a whole new level on national television in February 2008. When we originally discussed the idea of mixing up a batch of cornstarch and water with the producers of The Ellen DeGeneres Show, there was little interest: they thought it would be just a little tabletop experiment. When we shared the much grander idea of mixing up a batch of cornstarch goo that was large enough to fill a giant tub — and then inviting Ellen to walk across the surface without sinking — well, this was a quicksand experiment on a MUCH larger scale. The producers gave us the green light!
The challenge was to turn this kitchen chemistry activity into a large-scale demonstration. Rather than buying one box of cornstarch in this cornstarch activity, we needed a whopping 2,500 boxes of cornstarch! Anyone who has ever played with this cornstarch and water mixture knows that the bigger the batch gets, the harder it is to mix. If Ellen (or anyone else, for that matter) was going to walk on water, my team and I would have to find a way to mix up a HUGE batch!
That’s when my team of mixologists pitched the idea to the Bonanza Concrete company in Burbank, California. If one pound of cornstarch in a mixing bowl is fun, then 2,500 pounds in a cement truck would be a blast. Right?
In this quicksand activity, our goal was to mix up a batch of cornstarch goo large enough to fill a giant bathtub — and then attempt a quick run across its surface. The weight of someone’s body should cause the liquid to turn into a solid for a split second, allowing the person to literally run across the surface. Well, that was the theory anyway.
Let’s start with the giant bathtub: the props team on The Ellen DeGeneres Show (a very creative and talented team of people who can pull off just about anything) constructed a container 7-feet long, 3-feet wide and 1.5-feet deep that held about 240 gallons of water. After mixing up several test batches, we discovered that the mixing ratio of ten parts cornstarch to one part water worked beautifully. Given the size of the tub, we would need roughly 2,400 pounds of cornstarch to mix with the 240 gallons of water.
Since this original quicksand activity stunt first aired in February 2008, the Bonanza Concrete company has mixed up many more batches of cornstarch goo for game shows, educational programs — even a competition on a reality TV show. Back to our motto: “Make It Big, Do It Right, Give It Class.” Classy? Maybe not, but it sure made an impression!
The Quicksand Experiment — Steve Spangler Science Style
Although your classroom, home or club experiment won’t be quite as large as a giant bathtub on national television, you can still learn a lot in this easy cornstarch activity. Along with a great lesson in viscosity, this quicksand experiment is an entertaining way to see just how fun chemistry can be! For other hands-on experiments that will keep kids laughing, asking questions and learning about science in their everyday worlds, check out our other science activities for kids. These hands-on kids’ science experiments will apply fundamental scientific principles with simple demonstrations that are guaranteed to leave memorable impressions. Check out our online library of science experiments. From energy experiments and chemistry experiments to table tricks and food science, there’s a whole world of science waiting to be explored!