[♪ INTRO]
Hi there!
Squeaks and I were just talking about one of our favorite summer foods:
Fruit salad!
Making a fruit salad is just a matter of taking pieces of fruit
and mixing them all up in a bowl.
What can be hard is deciding what yummy fruits to include!
What would you like to add, Squeaks?
[Squeaks squeaks]
Ooh, good choices.
Squeaks would make sure he had cherries and watermelon, while I’d pick…
Hmm, let’s see, pineapple and blueberries!
Blueberries are my favorite parts of a fruit salad.
In fact, sometimes I eat all of the other fruit first, and save the blueberries for last.
It’s not really that hard to do,
because the pieces that make up a fruit salad mixture are still there.
Mixing them together doesn’t change them!
But sometimes, mixing two things together results in what’s called a chemical change.
During a chemical change, the things that get mixed together become something new!
So we can’t pull them apart very easily,
like we can with the mixture of fruit in our fruit salad.
[Squeaks squeaks]
Sure we can try to make a chemical change happen!
This experiment will be super fun, and very messy, so it’s a good thing we’re outside.
We’re going to make something that looks a lot like toothpaste…
and I think there’s going to be a lot of it — so much that an elephant could brush its teeth!
Now, if you’re going to try this at home, it’s really important that you do this safely.
That means you need help from an adult, and some safety glasses or goggles.
For this experiment we’re going to need an empty plastic bottle, a funnel,
a measuring cup and spoon, some dry yeast, warm water,
food coloring, and some liquid dish soap.
Finally, we’ll need something called hydrogen peroxide.
[Squeaks squeaks]
That’s right!
Sometimes adults will use hydrogen peroxide to kill germs,
so you might have some at home.
Oh! And you might also want to do this experiment on a large tray or in a large tub.
[Squeaks squeaks]
Ohh, you’ll see why, Squeaks!
Now, let’s get started.
First thing — safety first!
Glasses… on!
Next, we’ll mix our yeast and warm water together and wait for at least 30 seconds.
It’s okay to wait a little longer, though, so let’s get the other part of the experiment ready.
We’ll pour our hydrogen peroxide into the bottle using the funnel.
Next, we’ll add a few squirts of dish soap.
And swirl the bottle so that everything mixes together.
Let’s check on our yeast.
Oh, look at our yeast mixture, Squeaks!
What do you see?
[Squeaks squeaks]
Ooh, I do too!
The yeast and water mixture is kind of bubbly.
[Squeaks squeaks]
I agree!
While it is bubbly, it doesn’t look like toothpaste, and there’s not a lot of it.
And if we look at the bottle,
we can see there’s nothing in there that looks like toothpaste, either.
But I think we’re ready for our chemical change to happen!
We’ll quickly pour the yeast mixture into the bottle on the count of three.
Ready?
One…Two…THREE!
Oh, and look at all the foam!
There’s SO MUCH of it!
What else do you notice about it?
[Squeaks squeaks]
Do you think it looks at all like what we started with?
[Squeaks squeaks]
Me neither!
And look, there’s no way we could pick what we started with out of this mixture.
Do you notice anything else?
[Squeaks squeaks]
Ooh, yes!
The bottle feels warm.
And that warmth is a clue that a chemical reaction took place!
Some chemical reactions, like this one, release heat.
And bubbles are also often a way to tell that a chemical reaction took place.
If we look closely at the foam, we can see that it’s made of TONS of tiny bubbles!
Another clue.
So I’d say that we definitely had a chemical change take place in our experiment.
We’ll leave our goggles on until we’re done getting cleaned up, Squeaks.
Then we can talk about what happened!
Let’s start by looking at what we started with:
We had yeast, water, dish soap, food coloring, and hydrogen peroxide.
And what we have now doesn’t look like any of those things.
A chemical change happened, so we can’t go back to what we started with!
But some changes can be reversed.
If you put some water in the freezer, after a while it will freeze into solid ice.
And if you take that ice out and put it in the sun or on the counter for a little while,
it will melt into liquid water again.
So, you get back what you started with!
But our chemical change isn’t reversible like that.
Our toothpaste won’t go back to being soap and yeast and everything else.
Can you think of any other changes that aren’t reversible?
[Squeaks squeaks]
Oh, yeah!
When you heat up an egg, it goes from runny and gooey, to cooked and yummy.
But even if you don’t finish your breakfast and leave the egg out for a while, it stays cooked.
The change wasn’t reversible.
But speaking of yummy things, remember that fruit salad mixture we were talking about?
I’d sure love some of that now.
So let’s go and make some!
[Squeaks squeaks]
Thanks for joining us here at The Fort!
If you want to keep learning and having fun with me, Squeaks,
Mr. Brown, and all our other friends,
be sure to hit the subscribe button, and we'll see you next time on SciShow Kids!
[♪ OUTRO]