My kids and I did this experiment about a year ago and it was a lot of fun to do. But we didn’t fully understand the concepts covered, like density and buoyancy, so we redid it.
Goal of the experiment was to show how salt water has more density than plain water, which will make the egg float. Floating is buoyancy.
Supplies: a glass cup, enough water to fill half the cup, an egg (uncooked), salt, and a spoon to stir.
Instructions: The recipe called for a certain number of tablespoons of salt with a specific ounce of water, but I just decided to do it my way. See what happens. Even when I follow instructions, it’s a hit or miss. It’s all a learning process anyway.
We filled 3/4 of water in a tall glass cup, added (around) 4 spoon fulls of salt and stirred away. Once the salt particles dissolved, we gently plopped the egg into the cup. It floated down. After many tries of adding salt, stirring, and dropping the egg into the cup, we finally got the egg to float.
The process was slow since the egg had to be gently spooned out of the cup each time we needed to add and stir the salt. Many tries later, the egg finally floated; even with a poke down, the egg bounced back to a float.
SURPRISING RESULT, as a result of not knowing what to do with the egg post experiment: That cup of salt water and egg has been sitting on our kitchen counter for a month now. This was an interesting find…unexpected results! In the beginning, the water level was at the third ring from the top.
Post observational findings:
- water slowly evaporates
- even with evaporation, the egg still floats
- salt crystals formed on top of the egg
- No changes occurred on the egg
- Still floating, laden with salt crystals on top
- After most of the water evaporates, we’ll crack the egg to see if it’s changed
If you have an extra egg and time on your hands, you should try this experiment and see what you find!
I hope I covered the concepts correctly. I’m learning with the kids too and piecing my science knowledge one experiment at a time.