Well, your balloon might not quite fly away in this experiment, but you can make it inflate by creating a reaction in a bottle.
The warm water made the yeast "wake up" and it immediately started to have a chemical reaction with the sugar. Two substances, yeast and sugar, reacted to each other and together they made a new substance - a gas called carbon dioxide. Carbon dioxide is the same gas that makes soda pop fizzy, and one of the many gases in the air we breathe in and out. The carbon dioxide from the reaction filled up all the space in the plastic bottle and kept rising to fill up the balloon. At first, the yeast should have have looked puffy or bubbly on the surface of the water as it was beginning to react with the warmth of the water. Then, you probably noticed that the balloon was standing straight up instead of being flopped over the mouth of the bottle! That was the first sign that the yeast was reacting with the sugar and that carbon dioxide gas was being made. Soon after that, the balloon should have started to inflate. Since the balloon was made of stretchy rubber (and you helped stretch it out), it kept expanding to hold the carbon dioxide, the same as it would if you were to blow it up with your mouth. When you breathe out (or exhale), your lungs push carbon dioxide out, along with a few other gases, which is how you are able to blow up a balloon.
Now that you know how it works, you might want to try the experiment with other types of sugar mixtures. What do you think would happen if you used your favorite soda or juice instead of the sugar water?
So, if yeast and sugar react this way in a bottle, what happens when you bake with them? Well, the same thing happens, it just looks a little different. Bread and many other baked goods are made from yeast. The yeast reacts with the sugar in the dough and releases carbon dioxide, which creates tiny air bubbles that pop and leave air pockets as the dough bakes into bread. You can get a closer look at the air pockets left behind in a slice of bread.
The slime you just made is called a polymer (say: PAUL-UH-MER). The word polymer means "many parts." White glue is one type of polymer. When you mixed water with the white glue, the glue formed long chains of thousands of little molecules that you couldn't see until you added the Borax solution. The Borax had a reaction with the glue - it linked all those chains together, which made the whole mixture thicker and turned it into a blob of slime, a different type of polymer!
There are lots different types of polymers, including plastic, rubber, Jell-O, glue, camera film, materials such as nylon, and even natural fibers from wood and cotton. This polymer has properties of a solid and a liquid at once. Compare your polymer to a solid object - a piece of chocolate. Break the chocolate in half. Try quickly breaking the wad of slime in half. Did you get a clean break similar to the way the chocolate broke? To see how it is also like a liquid, try slowly stretching the blob out between your hands. You can't do that with a solid piece of chocolate! The polymer is showing its liquid properties when you stretch it slowly. Now set the slime back into the bowl you made it in and watch what happens. It should flatten out to fill the bottom of the bowl, similar to a liquid like pancake batter would do.
Chemical reaction- when two or more substances come into contact and form a new substance.
Carbon Dioxide- a gas that is in the air on earth, but in very small amounts. Plants need it in order to live; they use it to covert sunlight into food. Humans breathe out carbon dioxide when we exhale. In chemistry, it is abbreviated CO2, which means that is has one carbon atom and two oxygen atoms.
Polymer - the word "poly" means many, so a polymer is a long chain of molecules that gives a substance the ability to stretch and be very flexible.