- You will observe that chewing is part of a chemical reaction envolving starch.
MATERIALS NEEDED:
Bread
Tincture of Iodine
Eyedropper
Waxed paperPROCEDURE:
From a slice of white bread, cut two small pieces about one-inch square.
Place one piece in your mouth and chew it 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 wax paper.
Place the second dry piece of bread on a separate piece of wax paper.
Add four drops of iodine to both bread pieces.RESULTS:
- The unchewed bread turns a dark blue-purple. The bread-saliva mixture does not turn dark.
- The starch in the bread combines with iodine to form a blue-purple molecule. Chewing the bread mixes it with saliva. The saliva contains the enzyme amylase, which chemically changes the large starch molecules to smaller sugar molecules. Sugar does not react with the iodine, thus no specific color change.
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- The unchewed bread turns a dark blue-purple. The bread-saliva mixture does not turn dark.
CHEMICAL REACTIONS
IN YOUR MOUTH
INTRODUCTION: