How to make a bubble bottle

Create a simple lava lamp at home using household ingredients

Step 1. Make it bright

First take a clear plastic bottle. You can use a small bottle or a large two-litre bottle, any size works, but large bottles will require more materials! Fill the bottle around one-third of the way with water, and then add some food colouring; around ten drops should do for smaller bottles. You can use whichever colour you want, but orange and blue work well.

Step 2. Add some oil

Fill the rest of the bottle almost to the top with vegetable oil. You’ll notice the water and oil don’t mix; the oil sits on top of the water because it is less dense. They don’t mix because water molecules are attracted to each other and the oil molecules are attracted to other oil molecules, so they will not combine and you should be able to see a clear line of separation between the two.

Step 3. Make it bubble

Now drop a fizzy vitamin tablet or an Alka-Seltzer tablet into the bottle to start the fizzing. This will work better if you break the tablet into smaller pieces first. The tablet is made from a mixture of chemicals that react with each other in the presence of water to form carbon dioxide gas. These bubbles are lighter than the liquids, so they rise to the top of the bottle

Step 4. Light it up

As these bubbles rise they will pull some of the coloured water up with them, making streaks of colour burst through the oil. Put the lid tightly onto the bottle (otherwise it might bubble out of the top) and tip the bottle over a couple of times to make the blobs move even more. If you put a bright flashlight underneath the bottle, it will light up like a real lava lamp!

Step 5. Add more stuff

When the bubbles stop appearing, open the lid again and drop in another broken up tablet to start the process all over again. You can also try dropping some raspberries or other small and light fruits into the bottle — they’ll float between the layers of water and oil. When you add the tablet into the bottle how does the fruit react to the bubbles?

In summary…

The fizzing tablets create carbon dioxide gas in the water, and these bubbles carry some of the coloured water with them as they rise. When they reach the top of the oil, the bubble burst, allowing the gas to escape and the water sinks through the oil. This creates streaks and balls of coloured liquid in the oil, just like a lava lamp!


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