Surprised by the title! Well the purpose of this is to show that chewing is part of a chemical reaction.
Things Required:
Bread
Tincture of Iodine
Eye-dropper
Waxed paper
Directions:
Cut two small pieces from a slice about one-inch square from a piece of white bread. Place one piece in your mouth and chew it for 30 times. It will become very mushy. Make an effort to mix as much saliva as possible with the bread. Spit the mushy bread and saliva mixture onto a piece of waxed paper. Place the second dry piece of bread on a separate piece of waxed paper. Add four drops of iodine to both bread pieces.
This Is What Happens:
The unchewed bread turns a dark blue-purple. The bread-saliva mixture does not turn dark.
Science Behind It:
The starch in the bread combines with iodine to form an iodine-starch molecule. These molecules are blue-purple in colour. Chewing the bread mixes it with saliva. The saliva chemically changes the large starch molecules to smaller sugar molecules. Sugar does not react with the iodine, thus no specific colour change.
