May 18, 2024


Secret Code on an Egg

  • What you will need
  • White boiled egg
  • White vinegar
  • White crayon
  • Jar

In this fun experiment, we are going to learn how to write a secret message on an egg


  • Use your white crayon to write a secret code or message on your egg.
  • Place the egg in the jar.
  • Cover the egg with vinegar and let it stand for three hours.
  • Pour off the vinegar.
  • Cover the egg again with fresh vinegar and let sit for another three hours.
  • Remove the egg and carefully give it a wash.
  • The shell will be fragile but the area where you left a secret code should remain and be apparent

What Is Happening?

The vinegar is an acid and the eggshell is made of calcium carbonate which is a base. When an acid and a base come into contact with each other, a chemical reaction occurs. This reaction releases carbon dioxide. Look closely and you will see tiny carbon dioxide bubbles on the eggshell that is the result of the chemical reaction. The white crayon is hard to see on the white egg shell, making it easy to leave a secret message. The wax from the crayon will protect the egg shell from the vinegar. As the vinegar depletes the eggshell over time, the area under the crayon remains untouched and your secret message becomes revealed.

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