Lava Lite Copper Caper Water Clock Betcha Can! Blue Goo! Dancing Raisins
Compass Points Layered Liquid Stalk Show Quick Changes Balloon Galore
Ice Cream Made Easy! Edible Fibre Optics

Simply follow the instructions below and observe the exciting outcome!!.

Pour the grape juice into the glass.
Slowly mix the baking soda into the grape juice. The colour at the top of the juice will change to blue.
Now add the vinegar to the mixture, a drop at a time. The colour will change to pink where the vinegar drips.
When you pour out the liquid in the sink, notice how dark it has become.

Why?

Grape juice looks purple because its molecules are arranged in such a way that it absorbs all the colours of light except purple. The purple reflects back to your eyes. This is how you see colour. Adding other substances changes the molecular structure of grape juice, so its colour changes.