Secret writing

invisible ink or secret writing. Lemon juice is often used as one of the substances to make invisible ink.

The chemistry behind this technique involves the acid-base reaction between the lemon juice and the paper. Lemon juice is acidic, and when it is applied to paper, it weakens the fibers and breaks down the cellulose in the paper. When the paper is heated, the heat accelerates the breakdown of the cellulose, causing the paper in the areas where the lemon juice was applied to brown.

To reveal the message, the paper is either held over a heat source, such as a light bulb, or a chemical is applied to the paper, such as iodine or a baking soda solution. The heat or the chemical react with the acidic lemon juice and cause the message to become visible.

This technique is a simple and fun way to create secret messages that can only be revealed by those who know how to decipher them. However, it should be noted that this technique is not very secure, as the message can be easily revealed by someone who knows how to look for it