Make Square Bubbles
Water molecules (and also liquid soap and glycerin molecules) tend to stick to themselves.
This cohesive force creates surface tension.
(Note: Water by itself doesn’t form long lasting bubbles because a thin layer of water molecules evaporates too fast.
By adding soap and glycerin, the “skin” of the bubble is more stretchy and water is also prevented from evaporating too quickly.)
Because of this property, we can make a square bubble.
You can also make bubbles that look like a block or a prism.
Try this fun experiment and other fun water science project ideas.
How To Make Square Bubbles
Here is an exercise to make square bubbles.
Materials
- pipe cleaners
- liquid dish soap
- glycerin
- water
- drinking straw
Tools
- deep container
- adult superv
Instructions
- Bend pipe cleaners to form a cube. Leave a little bit out at one corner as the handle.
- Fill the container with water deep enough for the cube you just made to submerge completely.
- Add liquid dish soap into the water. For each cup of water, add 1/5 cup of liquid soap.
- Add glycerin to the mix. For each cup of water, add 1/10 cup of glycerin.
- Now you get your bubble solution, it’s time to test..
- Submerge the cube into the water entirely and then lift it up.
- Shake the cube gently from side to side to get different shapes of bubbles formed inside.
- Observe how the shapes of bubbles are different from those of free flying bubbles.
- With enough practice and trials (and patience), you will get a square in the middle ????
Notes
There is another way. Here is method 2.
- Submerge the cube into the water entirely and then lift it up.
- Set it onto a flat surface.
- Dip the drinking straw into the bubble solution to make the end wet.
- Positioning the drinking straw above the cube, blow a small bubble and let it drop down into the cube.
- Again, with enough practice and trials (and patience), you will get a square in the middle ????
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Why
There are several reasons why regular bubbles are spheres in shape.
While air blown into a bubble tries to stretch the skin out, surface tension of the solution tries to pull the skin in.
Given different shapes with the same amount of volume, a sphere has the smallest surface area.
That means the liquid molecules can stick closest together.
That is why free floating bubbles are always spherical.
Another reason is that, free from external interference, the pressure applied on the bubble skin from both inside and outside is equal all around a sphere.
Besides sticking to themselves, water molecules also tend to adhere to other surface.
When a cube frame is used, water sticks to the side of the pipe cleaner in addition to clinging onto its water molecule neighbors.
When you first dip the cube into the solution and lift it out, you may see a water film formed on each surface of the frame.
As you shake it or add in an extra bubble (method 2), the films touch other films to form different shapes inside the frame.
One of those shapes is a square bubble inside the square frame.
But notice that even when it’s “square”, the sides still curve and bulge slightly.
If you dip the frame into the solution multiple times (method 1), a little bit of air is trapped inside each time.
That can also create different shapes inside the cube due to cohesion and adhesion properties of liquid.
Here is what it looks like if you dip it into the soap mix over and over again.
And after making a square bubble, don’t let that bubble solution go to waste.
My 4 year old blew bubbles into it with the straw and had so much fun. She named this creation “a hundred bubbles”.
