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How to Make an Underwater Volcano

Learn how to make an underwater volcano for a science project with the instructions in this Howcast video.


Hi. When you guys think of natural disasters, number one natural disaster, when I ask my kids to make a prediction, to give me what they think is a natural disaster, everybody says, "volcanoes".

Now, when you guys usually make volcanoes it's always the same experiment. Baking soda, vinegar, kaboom. Baking soda, vinegar, kaboom. Okay, I'm a little bored with that. Watch this. And all we need is water. Water and food coloring and I can make something called "an underwater volcano".

See, volcanoes aren't just on land. They're also under water and when you see it actually erupt under the water your eyes are just like "What? How did that happen?" It's amazing. Now, check this out.

What I suggest you do first is just get some water, fill it up and put it aside for just about an hour so that it becomes room temperature. If you don't know what room temperature is, it is the temperature of the room. The temperature in Hawaii is going to be different than the temperature in New York, so the room temperature here will be different than the room temperature in Alaska. It doesn't matter where you live, it just matters that it is the temperature of the room that you're in.

What I'm going to do is, I think your cup should be clear, because if it is not clear you're not going to see it. Hello, it's a little boring, you want to be able to watch what is happening. So, I'm going to take a clear cup and I'm going to fill it up with water at room temperature. Just three quarters of the way.

Now, step two I am going to take a little vial. It doesn't have to be a vial, it could be a little container, it could be a baby food jar, just be creative. This is all about doing science using that you have at home. I am going to take this and a popsicle stick, again, if you don't have a popsicle stick you can use a tree branch. It can be anything that you have. I am going to take it and a rubber band and I am going to create a lowering device, because I am going to fill this up with extremely hot water. I take my rubber band, take the stick, wrap it around. Two, three, four, five and six.

Now, check this out, I created a lowering device. What I did was, you could use regular hot water from the tap, or if you wanted to make the water a little hotter ask your mom and dad to heat up some water, microwave, adult supervision though, please guys, you don't want to get burned, and what I am going to do is just add a little bit of red food coloring. Because, think about it, when you think of hot what color comes to mind? Red, I know, that's why I am going to make this red so that you, obviously, know it's hot. I am going to add about two or three drops of red food coloring, actually, you know what? I think it's cool if we make it even redder so let's add five more drops, one, two, three, four, five, six, seven wait, that's not five, sorry.

Now stir it around and I really don't want to touch it because it's hot. So, now I am going to take my lowering device and I am going to fill it up, do not leave any air at the top of your vial. I'm going to fill this up with water and you should not put your face close to it because the air bubbles are going to pop up and you don't want hot water hitting your face. That's not good. Fill it up and now I have my red very hot water.

Now the key to this experiment is do not tilt your vial, don't tilt it to the left, don't tilt it to the right, as you're taking it, you're going to lower it straight down into the water at the room temperature and whatever you do, do not let go of the stick, because then it would just float around. You want to take it and go straight down into the water at room temperature. I want everybody to make an observation. An observation in science is so important, you just watch very carefully what happens to all of the hot water. Are you ready? Want to do a countdown? Let's do a countdown, ready? Five, four, three, two, one and slowly lower it.

And if you drop the eye level, you're going to notice all that hot water is rushing to the top of the surface of the water at room temperature. Not one drop of the hot water is at the bottom of the container. It's all at the top, because the heat made the water molecules move faster and when the water molecules move faster, it became less dense than the water at room temperature and when water or air is less dense it rises. As you can see all of it rose to the top.

If you don't believe me, we can do the same experiment with cold water. We can do that right now. And if you look, it's still all red at the top, not a drop of it. But, eventually, when you leave the water there and it becomes water at room temperature the heat from the water will lower and the entire water will turn red, but, check this out.

Watch what happens if we use cold water. I'm going to do the same experiment. It's identical. Same materials. You have cup, water at room temperature, regular water, I'm going to make it really, really, really cold. You know what I'm going to do? I am just going to stir it around and while I stir it, let me ask you a question. When you think of the cold, what color comes to mind? It's not red, right? It's blue. Everybody thinks of the color blue when you think of cold.

So, to make this experiment fun, let's add blue. I'll add three drops? One, two, three. Stir it around. Taste? Tastes like nothing, food coloring has no taste. And, watch this. Vial, stick, same exact experiment, rubber band. The only thing I changed, if you want to think about variables, variables are things that could affect the outcome of the experiment. I am changing one thing, the temperature of the water, instead of using hot water we're using cold water.

I'm going to take my vial, exactly the same thing. I am going to fill it up. You really shouldn't try to get an ice cube in there. Now, what I love about science is that we can make predictions and it doesn't matter if you're right or wrong. Let's think about this, when you put the hot water into the water at room temperature you made an observation and all the heat rose. What do you think is going to happen to the ice cold water? The water molecules, now, are not moving around so fast, so what do you think is going to happen? Maybe. Right? Let's see. Let's check it out.

There is the water at room temperature, again, don't tilt it to the side, just go straight down and watch what happens. You're going to notice that all the cold is staying in the vial. Some of it came out, but if you look at the top of the water at room temperature, none of it is going to the top, because what I just did was make the ice cold water more dense than the room temperature water, so it's sinking and staying at the bottom of the water. So, actually, this experiment you could make water float on top of water, you can make water sink inside of water. Pretty cool, right?

And, that is my underwater volcano.

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