Once again, we are going to be using eggs to learn about science! In the past, we’ve used eggs to learn about osmosis and acid-base reactions.
Today, we are focusing on sedimentation and crystallization. After you learn about these concepts, you are going to make egg geodes!
Geode: A rock containing a cavity lined with crystals or other minerals.
The process by which particles (solute) suspended in a fluid (solvent) eventually come to rest due to the forces, such as gravity, acting on them.
Note: The solute and the solvent (the particles and the liquid they are suspended in) come together to form a solution. As you can see below, over time, the particles (green dots) in the fluid settle to the bottom.
The process in which solid crystals precipitate from a solution or melt (Crystallization can also occur when crystals form from a gas, but this is rare. In our activity today, we are focusing on crystals that form from a solution).
Can you think of a time that you’ve seen crystallization in the real world? I can! Back in November of last year, we did a snow blog (to see it, click here)! Snow flake formation is just one form of crystallization. Another form of crystallization is with natural crystals or gemstones. This takes a LONG TIME.
Check out this video to see crystallization in action!
You'll be creating your own geodes inside eggshells. They'll turn out looking similar to the geode below, except you get to make them whatever color you want!
- Push pin
- Small scissors
- White glue
- Small paintbrush
- Egg dye or liquid food dye
- Hot water
- Cup or container
- Drying area (rack, plate, or newspaper would work fine)
- Alum powder (you should be able to find Alum powder at any grocery store)
HERE’S WHAT TO DO!
1. Have you ever blown out eggs before you decorate them for Easter? That’s the first step to making egg geodes! You will need to carefully poke a hole in both the top and the bottom of the egg with the push pin. When you poke the hole, wiggle the pin around a bit to make the hole bigger. This will make it easier to blow the egg out of the shell.
2. Hold the egg over a bowl and blow on the top of the egg. The egg inside the shell should come out the bottom of the egg into the bowl. You can either throw the egg away, or go ahead and make an omelet! I suggest using your resources to have a great breakfast while you create your geodes :]
3. This part is tricky. Now that you have an empty egg shell, you will need to use a small scissors to break the shell in half the long way. Don’t worry about it being perfect. As long as you have somewhat of a bowl shape, you are good to go. If your eggshell completely shatters, just blow out another egg and try again!
4. Again, you will have to be extremely careful in this step! Use a piece of paper towel to wipe the inside of the egg clean. Next, use the small paintbrush to coat the inside of the shell with white glue. Before the glue dries, sprinkle the Alum powder generously over the glue so that it coats the whole inside of the eggshell.
5. WAIT!!! Your eggshell has to dry completely before you can move on. Leave it to dry overnight.
6. Up and at ‘em? Back to the grind! Measure two cups of water and heat it up. You can either heat it to boiling on the stove or put it in a microwave-safe container and heat the water in the microwave. Two to three minutes on HIGH should do the trick.
7. CAREFULLY pour the heated water into the cup or container that you plan on using to create your egg geodes.
8. Use a generous amount of food coloring to dye the water--30-40 drops is sufficient.
9. Add 3/4 cup of Alum powder to the colored water and stir it with a spoon until the powder is completely dissolved.
10. Let the Alum solution cool down for approximately 30 minutes.
11. Once the solution has cooled down, use a spoon to submerge your Alum-coated eggshell. Make sure the open side is facing up, and the eggshell is resting on the bottom of the container.
12. Now, the waiting game! Leave your eggshell to sit in the solution for 12-15 hours. Make sure you place the container in a safe place where no one will knock it over!
13. After 12-15 hours, prepare a drying area. Use a drying rack, newspaper, or paper plate. Use a spoon to remove the eggshell from the solution.
14. Check it out! How has your eggshell transformed? Make sure to take pictures and write down your observations!
- What happened to your eggshell? Describe the change it went through.
- How can you relate your eggshell’s transformation to sedimentation and crystallization?
- Try to explain the process your eggshell went through.
- When does sedimentation and/or crystallization occur in real life?
Here’s another fun activity about creating Alum crystals that will teach you a little more about crystallization!
Image and video credits, in order of appearance:
Juppi66, 2009. Ametyst-geode. Uploaded from Wikimedia Commons on 1/8/2017.
https://upload.wikimedia.org/wikipedia/commons/3/3b/Ametyst-geode.jpg File in the Public Domain.
Van Beek, 2017. Image created by Maddie Van Beek.
iseen, 2014. Beautiful chemical reactions - Crystallization. Video uploaded from YouTube on 1/8/2017. https://youtu.be/193qXKFMQR8
Heyde, 2007. Geode inside outside. Uploaded from Wikimedia Commons on 1/8/2017.
https://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Geode_inside_outside.jpg/800px-Geode_inside_outside.jpg File used in accordance with the CC Attribution-Share Alike 3.0 Unported. Image was not changed.
The Sci Guys, 2013. The Sci Guys: Science at Home: Crystallization of Alum - How to Grow Alum Crystals. Uploaded from YouTube on 1/8/2017. https://youtu.be/ojpCexbhxdU