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Surface Tension and Soap
Find out how bubbles work with this experiment. You won't actually blow any bubbles, but you will learn the science that makes a bubble!
What You Will Need:
What To Do:
Water is made up of lots of tiny molecules. The molecules are attracted to each other and stick together. The molecules on the very top of the water stick together very closely to make a force called surface tension. Surface tension is what caused the water to rise up above the rim of the glass in the experiment - the water molecules stuck together to make a dome instead of spilling over the side. Why didn't the dome break when you stuck your finger through it? Why didn't the water spill over the glass? Well, the surface tension was strong enough that it just went around your finger. The water molecules still stuck to each other and nothing spilled! What happened when you put your soapy finger into the water? The soap on your finger broke the water's surface tension and some of the water molecules didn't stick to each other any more and they were pushed out of the glass!
The force of surface tension also creates bubbles. In plain water, the surface tension is strong and the water might make some bubbles, but they will not last very long and they will be very small, because the other molecules in the water will pull on the bubbles and flatten them. Soap needs to be mixed with the water to make bubbles that can float through the air. When you add soap, the water becomes flexible, sort of like elastic, and it can hold the shape of a bubble when air is blown into it.
Super Bubble Solution
Make your own bubble-blowing solution out of soap and water, then see what happens when you add a special ingredient to the bubble solution!
What You Will Need:
What To Do:
The first bubble solution was just soap and water. As you learned from the Surface Tension experiment, soap helps bubbles form. You probably got some small bubbles that didn't last very long from the soap and water. Then you added glycerin or corn syrup to the soap and water and probably noticed that the bubbles you blew were stronger and better than before. Did they last longer? Were they bigger? The glycerin or corn syrup mixes with the soap to make it thicker. When the water that is trapped between the layers of soap in a bubble evaporates (or dries up), the bubble will pop! The thicker skin of the glycerin bubble keeps the water from evaporating as quickly. You can probably also blow a much bigger bubble with the second bubble solution that you made than with the plain soap and water one. Adding glycerin or corn syrup makes bubbles stronger and helps them last longer. It makes super bubbles!
After you make the super bubble solution and let it set for at least one day, try doing some of these cool bubble tricks! Can you think of any of your own tricks to do with bubbles?
What You Will Need:
How To Do The Tricks:
Trick 1 - A Square Bubble?
You will need two pipe cleaners and your super bubble solution for this trick.
The bubble was round even though it came from a square! Bubbles are always round when they detach and float through the air because the skin of soap always tries to take up the least amount of space it can and still keep the same amount of air inside the bubble. The soap molecules always stretch into a round shape automatically! A round shape takes up less space than a square shape. Try the trick again, but make a wand in any shape you want - what about a star or a triangle? Do bubbles from those shapes become round too?
Trick 2 - Don't Pop the Bubble!
You will need the super bubble solution, the lid from the container, a straw, and some objects with pointed ends.
You should have been able to push the scissors through the wall of the bubble without popping it! When something wet touches a bubble, it doesn't poke a hole in the wall of the bubble, it just slides through and the bubble forms right around it. The bubble solution on the scissors filled in the hole that would have been made. If you try poking dry scissors through your bubble, you will see it pop instantly! (If it popped when you put the wet scissors in, something was probably too dry. Try it again and make sure anything that touches the bubble is completely wet with bubble solution.) For another trick, get one hand completely wet in the bubble solution then use the other hand to hold your bubble blower and blow a big bubble in the palm of your wet hand.
Molecule - a very tiny part of a substance that is too small to see with your eyes. A water molecule is smaller than one drop of water!
Surface tension - molecules in a liquid are attracted to each other and make the top of the liquid very tight. The surface tension is what causes water to form drops. It also makes a dome shape across the top of a container that is filled to the top.
Evaporate - when a liquid dries up and goes into the air. The liquid is then in the air, but it is a vapor or a gas now and you can't see it. When we say the air is humid, it means that a lot of water has evaporated into the air and now water vapor (gas) is floating around in the air. It makes the air moist and heavy, and it might make you feel sticky when you go outside.