Try some of these fun (and tasty!) experiments to learn more about chemistry that can happen in your kitchen.
Jell-O Play Dough
This fun homemade dough can be played with and eaten! It is fully edible, and can be squished, rolled, and shaped. Try using molds or cookie cutters to shape it, or find simple tools to use such as forks, plastic straws, toothpicks, etc.
The play dough you made can be stretched, rolled, pushed, and pulled. It's flexible and stretchy, yet it also holds its shape when you mold it. This happens because of a reaction (or chemical change) between the dry ingredients and the wet ingredients. The water and oil don't mix - do they? It's like they don't like each other, and water doesn't want to be near to the oil. When you mixed the water and oil in with the dry ingredients, something happened. The water mixed with the dry ingredients, and suddenly it didn't mind being close to the oil. All of the dry and wet ingredients mixed together to make a thick solution.
Did you notice air bubbles in your homemade play dough? Between the bits of flour, water, oil, and Jell-O, there are tiny bits of air trapped inside. How did they get there? It happens because Jell-O contains an ingredient called gelatin. Gelatin is made up of long strands (almost like a necklace) of proteins. These protein necklaces stick together, making a stringy web. When you add water and heat, the webs become sticky, like a pile of spaghetti noodles. The Jell-O absorbs water, but it also traps air bubbles between the sticky strands of proteins. Even though your play dough feels smooth, the reason it can be stretched and rolled is because of these tiny strands of gelatin (so small you can't see them) that hold everything together. The oil helps to keep the dough from being too dry. The cream of tartar keeps the dough from being too sticky and also works with the gelatin to make the dough light and fluffy.
Another kitchen ingredient that has gelatin is a bag of marshmallows! That is part of what makes marshmallows so light and fluffy. Here are some fun science projects you can do with this delicious treat.
The two main ingredients in marshmallows (and marshmallow cream) are sugar and water. These sweets are light and fluffy because they have tiny bits of air trapped inside of them. When you put the marshmallows in the microwave, the air inside of them gets very warm. The sugar in the marshmallows also melts a little, becoming softer and more flexible. Have you ever heard that hot air rises? Hot air always wants to be on top. When you heat the marshmallows, the hot air pockets want to rise to be at the top. Since the marshmallow being heated in the microwave is soft and flexible, it stretches to allow the air inside to move. As the hot air is moving up, it pushes on the walls of the marshmallow, and the marshmallow gets much bigger, puffing up from the movement of hot air.
Along with sugar, water, and air, marshmallows contain gelatin. Remember that gelatin is like a long sticky string, or necklace? Gelatin is what makes a marshmallow hold its shape. There is not as much gelatin in marshmallows as there is in Jell-O, which means that marshmallows aren't slippery and sticky like Jell-O is. To make a dough with marshmallow cream, we added another sticky ingredient: peanut butter. The oils in peanut butter, along with the sugar and tiny bits of air in the marshmallow cream, mix together to make a smooth, light, flexible dough to play with. Does it hold its shape well? If you use the fluffernutter dough to mold shapes with, you might notice that they lose their shape after a while. This is because the dough doesn't have as much gelatin and can't hold its shape as well as the dough made with Jell-O.
Whipping cream is a dairy product that contains a lot of milk fat. Cream is made by skimming off the top of a large tub of fresh milk, where most of the milk fat has floated to the top. It is used to make whipped cream, ice cream, and butter. All the fat from the cream is contained in tiny droplets, like mini balloons too small to see. When you shake the jar, these balloons break open, letting the bits of fat go free. All the fat is collected together the more you shake it, and eventually it all comes together to form butter. Once the butter is made, there is still extra liquid in the jar. This is the leftover part of the cream, once the fat has been taken out. If you tasted it, it might taste a bit like milk, which has a lot less fat in it than cream does.
Other kitchen science projects:
Make candy with maple syrup - watch it crystallize!
The science of spinning eggs - you will need a partner to experiment with raw and hard-boiled eggs.
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