Have you ever made an eggshell disappear? You can. In this osmosis egg experiment, you will explore chemical reactions, plasma membrane, and osmosis.
Eggs are specialized cells called gametes. Eggs have a membrane and a hard outer covering that function to protect the developing embryo and behave similarly to a cell’s membrane.
This can be divided into several parts and is a great lab to come back to again and again adding deeper science context each time. You start by making the shell disappear.
What are the signs that a chemical reaction is occurring?
You are going to use vinegar to cause a chemical reaction. For this reaction how will you know it is happening? BUBBLES.
Scientists know that bubbles in a liquid either come from air escaping to the surface. This air was either trapped in the liquid, to begin with, or a chemical reaction has occurred. In this case, the vinegar reacts with the shell of the egg and causes the release of carbon dioxide.
Using the scientific method
I’m a big believer in the scientific method so we did an experimental egg and a control egg. The question my kids had was, what will happen to an egg in vinegar? Their hypothesis was, an egg in vinegar will behave the same as an egg in water. As Dwight Schrute would say, “False”.
As mentioned above, the vinegar reacts with the components of the shell and causes the shell to disappear. This leaves the membrane behind and you get a rubberized egg.
Our initial results.
We played with them for a little while (over the sink) and even dropped it to watch it bounce, but eventually, it broke. Leaving the membrane behind. Then we were able to see that the inside of the egg was still raw. Of course, we had to “see” what would happen if we threw our control egg into the sink.
This is an experiment that we have circled back around to and added more concepts in. The first one was about the cell membrane.
Why is the plasma membrane known as a semi-permeable membrane?
Semi-permeable membranes allow some things to pass through the membrane and don’t allow others.
Using the naked egg as a model for the cell with the membrane around the egg acting as a cell membrane we could test the permeability of the membrane.
What happens to a cell surrounded by water?
We were able to test three different eggs in three different solutions to see if the eggs gained or lost weight. The weight was caused by the movement of water across the membrane (either into or out of the egg). The results were dramatic.
Grab our entire osmosis egg experiment so you can run your own experiment.