Thursday, December 20, 2012

Exploration and Observation: Tasty Chemical Reactions!

On page 3 of The Best Christmas Pageant Ever, we learn that the Herdmans burned down Fred Shoemaker's old broken-down toolhouse when they started a fire with Leroy Herdman's "Young Einstein" chemistry set. Let's do some chemistry that's more fun and much, much safer!

So what is chemistry anyway? It's studying matter and how it reacts and changes. Everything around you is matter--you are matter! And there are chemical reactions happening all around you and even inside of you right now.

How do we know when we're seeing a chemical reaction? Here are three big clues:

1. A gas is released. Sometimes you'll see this as bubbles or notice an odor (usually a different one than what you started with). And since you're probably thinking of times when your body releases gas, I'll just tell you that farting and burping aren't chemical reactions themselves, but they do mean that chemical reactions are taking place inside your body. (They smell different than the food you eat. Right??)

2. The color changes. Simple enough.

3. There's a temperature change. Sometimes that means things cool down and sometimes that means that a reaction gives off heat (and sometimes light too.) When anything burns, it's a chemical reaction.

Okay, let's put these into action and see some chemical reactions around us! I hope you're hungry for this one...

1. Open a can of soda and pour it into a clear glass. Which of the signs above do you observe? There's a gas forming! There's a chemical reaction taking place right there in your glass! In this one, carbonic acid is splitting into carbon dioxide and water. (If you want to make gumdrop molecules of all three of these from our previous activity, you can find out what carbonic acid looks like here.) So if you think your soda tastes more watery after all the bubbles are gone--you're right! The chemical reaction that makes the bubbles also makes more water molecules.

2. Roast a marshmallow. Which sign of a chemical reaction does this one show? The color is changing! (The chemical reaction here might be a little too complex for our gumdrops.) And as a bonus, there's a temperature change too! The temperature change is going to be pretty small unless you actually set your marshmallow on fire (which makes it taste worse but is still good science!) But any time you burn something, it's a chemical reaction giving off that heat.

3. Pop some popcorn. Which signs does this one show? There's an odor, but it's the same as the unpopped popcorn. There's a temperature change, but that's from the microwave or popper adding heat. The color is changing though, right? The starch in the popcorn is having its own chemical reactions. (Click here and scroll down to the starch section to see why this one would take way too many gumdrops to build a model.)

You did it! Three chemical reactions! Now sit back, eat your snack, and let your body do the rest of the chemical reactions for you.

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