De-shelled Egg in Concentrated Salt

When a de-shelled egg (with its protective shell removed chemically, leaving only the semi-permeable membrane) is placed in a concentrated salt solution, it will undergo osmotic shrinkage and visibly decrease in size within 5 minutes. The egg membrane acts as a selectively permeable barrier, allowing water molecules to pass through while largely restricting dissolved salts. Because the salt concentration outside the egg is much higher than inside, water moves outward from the egg's interior through osmosis, flowing down its concentration gradient toward the area of higher solute concentration. This process is called exosmosis.

As water leaves the egg, you'll observe the egg becoming flaccid, wrinkled, and noticeably smaller. The egg white and yolk lose their turgidity as the internal fluid volume decreases. If you were to subsequently transfer this shrunken egg into pure water or a hypotonic solution, the reverse would occur—water would move back into the egg through endosmosis, causing it to swell and potentially regain much of its original size. This demonstration effectively illustrates the principles of osmosis and serves as a tangible model for understanding how cells respond to different osmotic environments, similar to what happens when you place plant cells in hypertonic solutions (plasmolysis) or animal cells in various tonicity conditions.