Author: Maddie Van Beek
Have you ever seen a lava lamp before? Your parents might have one left over from when they were teenagers! If you haven’t seen one before, take a look at the photo below!
Have you ever seen a lava lamp before? Your parents might have one left over from when they were teenagers! If you haven’t seen one before, take a look at the photo below!
https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcT9vONaVzg9Xa0t61n_3KO70K27pPD6Yo0f-TntXpYUko2ltl0I9w
Lava lamps used to be super popular and seem to make a comeback every once in a while. The “lava” inside real lava lamps are made with colored wax, but today, you are going to make a much simpler version of the classic lava lamp using oil, water, and Alka-Seltzer tablets.
http://www.brisbanekids.com.au/wp-content/uploads/2014/07/6-DSC_0030.jpg
If you have been following our blog for a while, you may remember other Alka-Seltzer experiments we’ve done in the past. For example, you made film-canister rockets (http://discoveryexpress.weebly.com/homeblog/make-your-own-film-canister-rocket) and made bubbles float (http://discoveryexpress.weebly.com/homeblog/make-soap-bubbles-float)! As you know from these experiences, Alka-Seltzer has a fizzy reaction that occurs when you place the tablet in water. When Alka-Seltzer fizzes, it is actually releasing carbon dioxide gas. Check it out!
Now that you know a little bit about Alka-Seltzer and its reaction with water, let’s move on to the other aspects of this activity. Before you use any Alka-Seltzer, you need to actually mix oil and water to start your project.
As you might already know, oil and water do not like each other! Pour a glass of water and then add a drop of vegetable oil. What happens? The oil sits right on top of the water. You may have already known that oil and water don’t mix, but do you know WHY? Check out the video below for a little insight!
As you might already know, oil and water do not like each other! Pour a glass of water and then add a drop of vegetable oil. What happens? The oil sits right on top of the water. You may have already known that oil and water don’t mix, but do you know WHY? Check out the video below for a little insight!
Two main reasons that oil and water don’t mix are their different densities and charges. You might have already worked with liquid density when we made a liquid density rainbow. If not, check it out for more ways to learn about liquid density while making a liquid rainbow in a glass (http://discoveryexpress.weebly.com/homeblog/rainbow-in-a-jar-learning-about-liquid-density)!
http://www.science-sparks.com/wp-content/uploads/2013/07/Density.jpg
Basically, water molecules are packed more tightly than oil molecules. When molecules are more tightly packed, they are denser than other liquids or objects that have molecules that are less tightly packed. This means you might have two objects of the same size that are different densities.
Look at the image below. Which object is denser?
Look at the image below. Which object is denser?
http://inspirationlaboratories.com/wp-content/uploads/2012/11/density-comparison.jpg
Because one object is denser, it will weigh more. For example, look at the picture below. Even though the cork and the rock are about the same size, the cork floats while the denser rock sinks to the bottom.
https://lacerdapedro.files.wordpress.com/2013/03/2014-02-27-density.jpg
Essentially, half a cup of oil and half a cup of water look the same, take up the same space, but a half cup of water contains more molecules than a half cup of oil. This is why when water and oil are mixed together, the oil floats at the surface and the water sinks to the bottom.
The other reason that oil and water don’t mix is that water is polar and oil is non-polar. Because polar molecules only dissolve in polar solvents and non-polar molecules only dissolve in non-polar solvents, neither the water or the oil will dissolve when mixed together. Instead, the water molecules will stick to each other and the oil molecules will do the same.
Now that you know a little background information on your materials, let’s get started!
YOU WILL NEED:
Here’s what to do!
References
https://sciencebob.com/blobs-in-a-bottle-2/
http://www.stevespanglerscience.com/lab/experiments/bubbling-lava-lamp
https://www.questacon.edu.au/outreach/programs/science-circus/videos/oil-and-water
http://mocomi.com/why-oil-and-water-dont-mix/
https://en.wikipedia.org/wiki/Lava_lamp
The other reason that oil and water don’t mix is that water is polar and oil is non-polar. Because polar molecules only dissolve in polar solvents and non-polar molecules only dissolve in non-polar solvents, neither the water or the oil will dissolve when mixed together. Instead, the water molecules will stick to each other and the oil molecules will do the same.
Now that you know a little background information on your materials, let’s get started!
YOU WILL NEED:
- Empty plastic bottle
- Water
- Oil
- Alka-Seltzer
- Food coloring
- Flashlight (optional)
Here’s what to do!
- Fill your plastic bottle with vegetable oil until it is about 3/4 full.
- Pour water to your bottle until it is full, but not overflowing.
- Add about 10 drops of food coloring into the bottle. Take a moment to record your observations. What happened when you added the food coloring? Did it mix in with both liquids?
- You should have noticed that the food coloring changed the color of the water but not the oil. Why do you think that is?
- Next, break an Alka-Seltzer tablet into a few pieces and drop one piece into the mouth of the bottle. What happens? Lava greatness!
- If you want the full effect of the lava lamp, set your bottle on top of a flashlight and turn the lights off.
- As soon as the bubbling subsides, just add another piece of Alka-Seltzer to keep the party going!
References
https://sciencebob.com/blobs-in-a-bottle-2/
http://www.stevespanglerscience.com/lab/experiments/bubbling-lava-lamp
https://www.questacon.edu.au/outreach/programs/science-circus/videos/oil-and-water
http://mocomi.com/why-oil-and-water-dont-mix/
https://en.wikipedia.org/wiki/Lava_lamp
