Demonstrating Osmosis with eggs
An egg contains a semi permeable membrane underneath the shell, which can be used to
demonstrate osmosis. The eggshell is mostly made of calcium carbonate which will
dissolve in acid. Vinegar or hydrochloric acid are suitable. Stronger acids will dissolve
the shell faster, but are more corrosive. Vinegar takes several days.
Place three eggs in a beaker, cover them with acid and weigh them down so they
don't float above the surface.
Allow them to remain in the acid until the shells completely dissolve.
Then place each of the eggs in a different liquid:
o Place one in water
o Place one in an isotonic sucrose solution, [about 0.3M]
o Place one in a 1M sucrose solution
The next day remove the eggs and compare their size.
You will find that the egg in water will have swollen considerably. If you carefully pierce
the membrane with a needle a jet of water will shoot into the air. The egg in an isotonic
solution will be approximately the same size, while the egg in 1M solution will have
Educational Resource written by James Dauray | http://www.aurumscience.com 1