The egg shrinks because water moves out of it.
Explanation
The phenomenon observed is osmosis, specifically exosmosis. Osmosis is the movement of solvent (water) molecules through a semi-permeable membrane from a region of lower solute concentration (higher water potential) to a region of higher solute concentration (lower water potential).Detailed Analysis:
- Semi-permeable Membrane: A deshelled egg is surrounded by a semi-permeable membrane that allows water to pass through but restricts the passage of solute particles like salt.
- Hypertonic Environment: A concentrated salt solution is hypertonic relative to the fluid inside the egg. This means the external solution has a higher concentration of solutes and a lower concentration of water compared to the egg's internal environment.
- Mechanism (Exosmosis): Due to the concentration gradient, water moves out of the egg and into the surrounding salt solution. This outward movement of water is termed exosmosis.
- Result: The loss of water causes the volume of the egg to decrease, leading it to shrink.
Key Takeaway: When a cell or membrane-bound structure is placed in a hypertonic solution, water moves out via osmosis, causing the structure to shrink.