Bouncing Eggs

We use vinegar to remove the shells from eggs without breaking them. Two eggs are placed in a beaker of vinegar, but one is half coated with clear nail polish. The exposed shells dissolve over time and the eggs swell as more water moves through their semipermeable membranes. In the areas not protected by nail polish, the shell of the egg completely dissolves so that it can be examined using a torch and bounced gently.

Chemistry - Reactions - Learning Points.
Eggshells consist mostly of calcium carbonate (CaCO3).
Metal carbonates + acid ➔ salt + water + carbon dioxide.
Nail varnish can protect the eggshell from acid.
Osmosis occurs across the egg's semi-permeable membrane to equal the concentration gradient across it.

A Twig Experiment Film.
Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.