Rubber Egg

Rubber Egg

Soak a hard-boiled egg in vinegar to transform it into a rubbery egg that can bounce like a ball

Suitable for kids aged 4+ with parental supervision

You Need:
  • Hard-boiled egg
  • Glass or jar, big enough to hold the egg
  • Vinegar
What to do:
  1. Place the hard-boiled egg in the glass or jar.
  2. Pour enough vinegar into the jar to completely cover the egg. Look closely, what do you see? Can you see some tiny bubbles start to form on the shell? Why?
  3. When the shell has completely dissolved, after about 3 days or so, remove the egg from the jar and gently rinse it with tap water. How does it feel?
  4. Bounce your new rubber egg on a hard surface. How high does it bounce?
  5. As a further experiment, try soaking a raw egg in vinegar for 3-4 days, how does the raw egg compare to the hard-boiled egg soaked in vinegar? Gently squeeze the egg. How does it feel? We dont recommend you bounce this egg.

Why is it so?

Vinegar is a weak acid (acetic acid) and reacts with the calcium carbonate eggshell to produce carbon dioxide gas (hence the bubbles that form). Eventually the calcium in the eggshells is completely broken down by the acid and become a soft rubbery texture.