Mini-Project #1: Make Invisible Ink

How to Make Invisible Ink
Chemical Properties of Lemon Juice


Materials:

Half a lemon

Water

Spoon

Bowl

Cotton Bud (Swab, Ball)

White Paper

Lamp or other light bulb

Procedure:

1. Squeeze some lemon juice into the bowl and add a few drops of water.
2. Mix the water and lemon juice with the spoon.
3. Dip the cotton bud into the mixture and write a message onto the white paper.
4. Wait for the juice to dry so it becomes completely invisible.
5. When you are ready to read your secret message, heat the paper by holding it close to a light bulb.

Safety Precautions:

Safety first, goggles on!
The acid from the lemon can burn your eyes.

Scientific Principles:
Since lemon juice is acidic and also organic, an oxidation reaction occurs when heat is applied and the words will turn brown. Any other acidic substances will work as well. Catherine and I used vinegar as a substitute.





PHOTOCREDIT: Marcia Lee

The project itself failed slightly, as we did not have a lightbulb to hold the paper to, so we attempted sticking it close to the fire. The vinegar began to oxidize slightly, but we did not dare sticking the paper any closer to the fire. By the way, the message reads "HI! WE LOVE CHEM!"