Have you ever fancied yourself as a spy? In order to be a proper spy you will need to know how to read and write secret messages. In this experiment, Year 5 learned how to create them.
In the process they learned that iodine can check for the presence of starch and Vitamin C. In a bowl we mixed one tablespoon of cornstarch and a tablespoon of water. Using this mixture, we took a toothpick and wrote a secret message on a piece of paper. We waited for our message to dry to see the results. It was barely visible on the paper. Then we dipped our paper into an iodine mixture to reveal the secret message. “Happy Birthday” appeared in dark purple. It was no longer a secret and a nice surprise for the birthday boy in our class. This proved our theory that iodine reacts with the starch creating a dark purple message. The white paper also turned a lighter purple, due to the small amount of starch it already contains.
In order to make the message disappear again, we would just add lemon juice. When lemon juice is painted over top of the writing, the Vitamin C in the juice reacts with the iodine to make a new colourless compound and the writing disappears.
Year 5 have completed their first course in how to become a Spy. Who says Science has to be boring?