Purpose to observe the layering of undissolved materials.
Things Required:
2 tablespoonfuls of flour
2 tablespoonfuls of any large dried bean
Quart glass jar with a lid
Directions:
Place the beans and flour in the jar. Fill the jar with water. Screw the lid on tightly. Shake the jar to mix all the materials thoroughly. Let the jar stand undisturbed for 20 minutes. Observe.
This Is What Happens:
The beans settle first with a fine layer of flour on top.
Science Behind It:
The beans and flour are not soluble in the water. As soon as the shaking stops, gravity starts pulling the materials down. The heavier beans settle first. The tiny flour particles remain suspended in the water for a few minutes, but finally are pulled to the bottom of the jar. The mixing of materials that do not combine is called a suspension. Water in a fast-flowing stream forms a suspension by picking up rocks and soil that temporarily stay suspended in the moving water, but the materials settle out in layers on the stream bed when the speed of the water is reduced.
