Experiment 6: Density and Lava Lamps
What is Density?All matter is made up of teeny tiny particles called atoms. The more atoms there are in the same amount of space, the more dense an object is. Take a look at the illustration below:
You can see that Material A has a lot more particles packed in a given area than Materials B and C, while Material B has more particles in the area than Material C. Therefore, we can say that Material A is more dense than Materials B and C and Material B is more dense than Material C.
I know what you are thinking... WHAT DOES THIS HAVE TO DO WITH LAVA LAMPS? And WHAT ARE LAVA LAMPS? A little patience and your questions will be answered! What are Lava Lamps?Lava Lamps were a novelty item in the 1960s. It is basically a clear glass bottle containing paraffin (wax) and a clear liquid. Inside the base of the lamp is a 40 to 60 watt incandescent bulb which serves wo purposes. First, to provide lighting and second, to melt the paraffin. Once the paraffin has melted, it separates into blobs and moves up and down the liquid.
What is the connection between density and lava lamps?To make a good lava lamp, you need to use two liquid substances that are insoluble in one another and have very similar densities. In commercial lava lamps, paraffin and a clear liquid are used. Now, what's in the clear liquid? It varies from manufacturer to manufacturer. In the past, carbon tetrachloride was used as the clear liquid. However, it was banned because it was found out to be toxic.
Here is how it works... The paraffin is slightly denser than the clear liquid. When it is heated, it expands and then becomes less dense that the clear liquid. Hence, it rises to the top of the lamp. Away from the heat source, the paraffin cools down and becomes more dense than the clear liquid. Therefore, it sinks to the bottom where the heat source is. The cycle then continues until the lamp is turned off and the heat source disappears. The wax then collects at the bottom of the lamp, since it is denser than the clear liquid. So, how can we make our own lava lamp?Well, since is it an experiment for the young ones, we are going to make a simple lava lamp powered by chemical reaction rather than a heat source.
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The EXPERIMENT: Mini Lava Lamp
Our objective: To make a mini lava lamp powered by a chemical reaction rather than a heat source.
Our Materials:
Our Materials:
- small plastic or glass bottle with cover (Travel bottles will do nicely, however, if you want to do it on a bigger scale, a clean vinegar bottle will do. I was able to buy travel bottles in Japan Home Center.)
- colored water
- cooking oil
- about 1/8 tablet of Alka Seltzer (Use a bigger piece if you are using bigger bottle. You can buy Alka Seltzer in Watson's or Taste.)
The Procedure:
Fill 1/4 of the bottle with colored water. Pour in oil up to the neck of the bottle (where the cap is screwed on). Take about 1/8 of an Alka Seltzer tablet and insert it into the bottle. Do not put too much Alka Seltzer because the lava lamp will overflow. You can screw on the cap if you want to. Wait until the reaction is complete before adding another piece of Alka Seltzer. Have fun! |
For Parents...
Science is a great way to develop your children's critical thinking and logical reasoning skills! So, ask them to share what they did during science club. They should have brought home the products of the experiments or even some materials to do the experiment at home with you! Have a discussion about the experimental process and do extension activities! I promise that you will have as much fun as your children had and they will have a blast being your TEACHER!
Discussion Questions:
Extension Activities:
Discussion Questions:
- Which liquid is more dense -- water or oil? Why?
- What was the role of Alka Seltzer in this experiment?
- What made the water bubbles go up and down?
Extension Activities:
- What other liquids (aside from water and oil) can you use to make a mini lava lamp? Share your work with me! My email address is: [email protected]