How to Stack Liquids in a Rainbow of Layers: A Fun Kid Science Project
Ever try to stack liquids without letting them mix?
It’s easy and oh-so-cool! You just need a little chemistry know-how and a steady hand.
In this article I’ll show you how you and your kids can stack seven liquids into a rainbow of layers, one on top of the other, without mixing them.
It looks like magic, but it’s not—it’s science!
Why Stack Liquids?
It’s important to teach kids basic scientific concepts so they’ll understand how the world around them works.
When you make it fun or exciting or even jaw-droppingly awesome, you capture kids’ attention, pique their curiosity and make them want to learn more.
Stacking liquids achieves all three. And when you do it together with your kids, you make it an adventure!
So, let’s start with the science: This experiment is based on density. Think of this experiment like a liquid burrito.
Density measures how much mass is contained in a given unit volume (Density = Mass / Volume). Fancy words, but what do they mean?
Think of mass as the measure of how much stuff there is in an object or liquid.
Volume is the portion or how much there is of the object (for example 8 ounces [237 ml]).
Density is a measure of how tightly that stuff is packed together.
If the weight or mass of something increases, but the volume remains the same, the density has to increase. Likewise, if the mass decreases but the volume stays the same, the density has to go down.
Lighter liquids like water or rubbing alcohol are less dense or have less “stuff” packed into them. Denser liquids like honey have more “stuff” packed into them.
Learn more about mass, volume and density by viewing this presentation.
Now that you understand density, let’s make stripes.
Here’s a quick video to show you what we’re going to do:
Watch this video to see how the density column experiment works, then do the experiment with your family.
Watch with your kids to see how it’s done, then read on for step-by-step instructions.
#1: Measure and Color
Measure each type of liquid into one of the seven plastic cups. We used 8 ounces of each. Depending on the size of your glass container, you may need more or less of each liquid. The key is to use the same amount of each while also filling up the container.
Color the corn syrup, the rubbing alcohol and the water different colors for dramatic effect. You can also leave them clear but the layers won’t stand out as strongly. If you want to see all of the stripes, color those three ingredients.
You will layer the liquids in this order, starting at the bottom of the cylinder and working to the top:
- Honey – yellow/gold
- Corn syrup – we dyed ours red
- Dish soap – blue
- Water – colorless (dye it a color if you’d like)
- Vegetable oil – pale yellow
- Rubbing alcohol – we dyed ours green
- Lamp oil – We used red
Honey: Start the column by pouring the honey into the cylinder. Pour the honey into the center of the cylinder being very careful not to touch the sides while pouring.
It’s very important to let each layer settle before adding the next one. Take your time and pour slowly and carefully.
Corn syrup: Next, layer the corn syrup (we dyed ours red). Pour it carefully and slowly in the middle and don’t let it touch the sides.
Dish soap: Repeat the same procedure for the dish soap. Pour the soap directly into the middle of the layer of corn syrup and take your time pouring.
#3: Trickle Down
There’s a secret to stacking the less-dense liquids without mixing them…
Water: For the water layer, you will need to use the food baster (Ta-dah!). From this point forward, it’s okay to let the liquids touch the sides. In fact, it’s a must!
Dip the food baster into the water in the cup, squeeze the bulb and draw up some water.
Rest the tip of the baster on the inside wall of the cylinder and slowly squeeze the bulb. Let the water slowly trickle down the glass to create the third layer.
Vegetable oil: If you colored your water, rinse the food baster and fill it with the vegetable oil. Again, use the inside wall of the glass and let the oil trickle down the side.
Rubbing Alcohol: Since the oil will stick to the insides, wash the food baster with soap and water before you fill it with the rubbing alcohol. Use it and the inside wall to dribble the next layer.
Again, rinse the food baster and congratulate yourself. You are one layer away from a seven-layer science burrito.
Lamp oil: Draw up the lamp oil in the food baster and keep your finger over the tip while you transport it to the cylinder. Finally, use the glass wall and the baster to fill your last layer.
Take a bow and a big sigh of relief. Now, give each other a hug. You’ve done it!
How did your stripes turn out? Be sure to take a picture!
Caution: You may make this in a drinking glass, but make sure your kids do not take a drink of this experiment!
You can make a three-color density column that IS safe to drink, using different ingredients.
#4: Take it Further
If you want to create an even cooler science burrito, go on a scavenger hunt to find a few items around your house like a safety pin, key, staple, peanut, raisin, chocolate chip, small rubber bouncy ball, ping pong ball, etc.
Carefully drop each item into the center of the cylinder. Some items will stay near the top, others will sink part or all of the way down.
How Does it Work?
By understanding the science of density, we know the same amount or volume of two different liquids will have different weights, because they have different masses. The liquids that weigh more (have a higher density) will sink below the liquids that weigh less (have a lower density).
To test this yourselves, you can set up a scale and measure each of the liquids that you poured into your column.
Make sure that you measure the weights of equal portions of each liquid. You should find that the weights of the liquids correspond to each different layer of liquid. For example, the honey will weigh more than the corn syrup.
If you dropped objects into the column, observe the different densities of the liquids versus the different densities of the objects.
If the layer of a liquid is more dense than the object itself, the object stays on top of that liquid. If the layer of liquid is less dense than the object, the object sinks through that layer until it meets a liquid layer that is dense enough to hold it up.
Some Final Thoughts…
Encourage your kids to ask questions and test new liquids and objects. Do all brands of lamp oils exhibit the same characteristics or densities? What about corn syrup or vegetable oil? We smell the beginnings of a great science fair experiment.
In our experiments, we’ve also observed some of the layers switch places after the column sits for a few days. The layers of vegetable oil and rubbing alcohol switch places. The rubbing alcohol moves below the vegetable oil, indicating that the density changed. We are not exactly sure why the change occurred.
And remember the next time you are drinking iced tea, you will know why the ice cubes float. It’s all about density.
What do you think? We want to see your Liquid Layer Science Burrito. Share your family’s success story of the liquids you stacked and how many. Who can stack more than seven?
Images from iStockPhoto.
Steve Spangler is an author, teacher, toy designer, Emmy award-winning television personality and creator of a huge soda mess. His appearances on television demonstrate his passion for making learning fun. Other posts by Steve Spangler »