What Is a Decalcified Egg Experiment?

The classic decalcified egg experiment removes the shell from the egg and allows the experimenter to see the results of osmosis when the shell-less egg is placed into liquids. This activity is also a model for osmosis within a cell.

To begin the experiment, eggs are placed in vinegar for two to three days, until the shells have dissolved but the flexible membranes remain. The eggs are removed from the vinegar and dried.

Three beakers are prepared for the experiment. One has distilled water, one has a sugar water solution, using sucrose or maple syrup, and the third serves as a control and contains no liquid.

The experimenter observes the eggs over time to note any changes that occur. If everything works properly, the egg in the sugar solution decreases in size, while the egg in water becomes larger. Changes are observable within an hour, but a longer period produces more dramatic results.

Distilled water flows from the beaker into the egg. Osmosis occurs in this direction because the substances inside the egg are more concentrated than plain distilled water. Thus, the egg increases in size. With the other egg, the osmosis flow occurs from the egg into the sugar solution. This solution is more concentrated than what is inside the egg, so water flows out of the egg into the beaker, reducing the size of the egg.