Growing and Shrinking Egg
Bigger or smaller, these eggs use chemistry and permeability to expand and contract.
We’ve found a method to take our famous Naked Egg experiment to a new level. By dropping your Naked Eggs into Karo corn syrup or water, you’ll witness eggs that have the strange ability to grow and shrink. It’s all an investigation into chemical reactions and permeability that is fun and engaging.
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- Karo corn syrup
- Various glasses
- Adult supervision
- Fill multiple glasses with vinegar.
- Allow eggs to soak in vinegar for 24 hours. You will be left with the membrane, but no shell.
- Fill one glass with Karo corn syrup.
- Fill another glass with water and place one “naked” egg inside each glass. Allow the eggs to soak for 24 hours.
- Pull the eggs out of the glasses and observe what has happened. Notice how much larger the egg in the water is than the egg in the sugar solution.
Try creating sugar water solutions with varying amounts of sugar, then compare the relative size of the eggs after soaking.
How Does It Work?
You begin the Growing and Shrinking Egg experiment by dissolving the egg shells in vinegar. The vinegar’s acetic acid reacts with the calcium carbonate of the egg shell to produce carbon dioxide, calcium, and water. While you won’t notice the water, and might not see the calcium, you’ll definitely notice the bubbles of carbon dioxide gas form on the egg and release to the surface. The result is two “naked,” or shell-less, eggs
Once the eggs’ shells have vanished, you start the growing and shrinking process with Karo syrup and water. Karo syrup has a very high density that comes from a high concentration of dissolved sugar. These sugar molecules are too large to pass through the semipermeable membrane of the egg, but the water molecules from the egg can. These water molecules pass through the membrane of the egg into the Karo syrup until the concentration of water molecules is the same on both sides. The water movement, from egg to syrup, results in the shrunken egg.
The other egg that you soaked in water grew, but why? Just as the concentration of water molecules is higher in the egg than in the Karo Syrup, the egg has less water concentration than that of the water. In this glass, water molecules are moving into the egg, instead of out. The increase in water results in the expansion of the egg!