Invisible Ink with baking soda and vinegar

We can make non-toxic invisible ink using baking soda with in few minutes the advantages of using of backing soda are that it is safe for even kids, simple to use and cheaper

Reagents and Equipment 

1. Baking soda
2. Paper
3. Water
4. Light bulb(heat source)
5. Paint brush
6. Measuring cup
7. Purple grape juice (optional)

Step by step procedure

• Mix equal parts of water and baking soda.
• Use a tooth pick or paint brush to write a message in the white paper using the baking soda solution as ink.
• Allow the ink to dry.
• Ways to read the message 
1. Hold the paper up to a heat source or iron it. The baking soda will cause the writing in the paper to turn brown 
2. Paint over the paper with purple grape juice. As the concentration of grape juice increases visibility of color change increases.

Process

      Writing a message using baking soda solution disrupts the cellulose fibers in the paper, damaging the surface. When heat is applied exposed ends of fibers becomes darken. On applying too much heat, there is a risk of igniting the paper. So it is better to use either the grape juice or a controllable heat source

     The grape juice act as a pH indicator that changes color when it react with the sodium bicarbonate of baking soda which is a base. That acid base reaction.