A chemical reaction occurs when substances are mixed together and are changed. Sometimes substances mix together and not much happens, at other times the results are dramatic or just surprising, like in this demonstration. In this one you will mix two things together to make something that looks and acts totally different than the two things you started with! You can probably find the things you need to try this one yourself at home!
What You Need:
Pour 1/2 cup of milk into a large cup. Add 2 teaspoons vinegar. Mix. Place a coffee filter or paper towel over a second large cup. The coffee filter should sag a little bit to make a little filter bowl. Put a rubber band around the top of the cup so it holds the coffee filter in place. Now pour the milk/vinegar mixture into the filter bowl you made.
Let the liquid part of the mixture drip through the filter. This might take awhile. When the liquid is done dripping use a spoon to scrape the milky lumps off the coffee filter and into a bowl. Add 1/4 teaspoon baking soda to the lumps and mix. Is this substance getting sticky? Try it out - can you use it to glue two pieces of paper together?
What happened? When the milk and vinegar (an acid) mix together a chemical reaction takes place. A substance called Casein forms. Casein is a very long molecule that bends like plastic - that's why the lumps of milk are pliable and bendy. When you add baking soda (a base) to the milk lumps another chemical reaction happens turning the milk lumps sticky, like glue!
Science Experiment Idea: Make three batches of milk glue, but make the variable (the thing you change) the amount of baking soda you add to the mixture. If you add 1/8 teaspoon baking soda to one batch, 1/4 teaspoon baking soda to one batch and 1/2 teaspoon baking soda to one batch, which one will be the most sticky? Why do you think so? To investigate chemical reactions further - try some more experiments at home!
Science in Context: Chemical Reactions is a database you can use in any IndyPL Library Branch or at home. Login using your IndyPL library card number. The Science in Context database will show you articles, images and videos to help you learn about chemical reactions.
You can also ask a math and science expert for homework help by calling the Ask Rose Homework Hotline. They provide FREE math and science homework help to Indiana students in grades 6-12.
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